(Thomas, D.D.), so well known to the public by his moral and metaphysical writings, was the son of the Rev. Lewis Reid, minister of the parish of Strachan, in the county of Kincardine, North Britain. His mother was the daughter of David Gregory, Esq., of Kinardie, of whom some account has been given in this Supplement, and sister to David, James, and Charles Gregories, who were at the same time professors of astronomy, or mathematics, in the universities of Oxford, Edinburgh, and St Andrews.

He was born at the parsonage-house of Strachan in April 1710, and received the rudiments of his education at the parish school of Kincardine-on-Dee. At that period the parochial schools of Scotland were very superior to what they are now; and young men went from them to the university well furnished with philological learning. The progress of young Reid must have been rapid; for he was removed from school to the Marischal College, Aberdeen, when not more than twelve years of age; and we have never heard that he was admitted into the university before he was qualified to profit by the lectures of the professors. On the contrary, he soon displayed the genius of his mother's family, and became conspicuous among the students of mathematics in a college where that science had been at all times cultivated with ardour and success.

After the usual course of four years employed in the study of Latin, Greek, Mathematics, and Philosophy, he probably took his degree of M.A. which at that period, and for a long time subsequent to it, was the universal practice in the university of Aberdeen, and then commenced the study of theology. In due time he was licensed to preach the gospel according to the forms of the church of Scotland; but continued to reside for some years in Aberdeen, cultivating his favourite science, mathematics.

The mathematical chair in Marischal College was then filled by Mr John Stuart, a man of great eminence in his profession; but who, like many other profound mathematicians, was not happy in his mode of communicating science, at least to the duller part of his pupils. Mr Reid occasionally read lectures for the professor; and a friend of ours', by no means dull, has often been heard to express great satisfaction, that Mr Stuart was kept a whole winter from the schools, when he was a student, and that the class was taught by Mr Reid. "Had it not been for this circumstance (said he) I should never have understood more of mathematics than the first six books of Euclid's elements; but Mr Reid had the faculty of making every thing intelligible to the students which he clearly apprehended himself."

He could not, however, spend his life in the study of mathematics, and in reading barren lectures for other men. He had been educated for the church; and it was in the church only that he had the prospect of gaining a livelihood. He was accordingly presented, we know not in what year, to the church of New Machar in Aberdeenshire, at a time when the good people of Scotland were very far from being reconciled to the rights of patronage; and the consequence was, that his settlement met with much popular opposition. Even a little riot took place in the church at his ordination; but he soon gained the affections of his flock by his good sense, his acknowledged worth, and his unwearied attention to all their wants, which he was ever ready to relieve to the utmost extent of his abilities. So deeply rooted indeed was their regard for him at last, that, though it is now almost half a century since his relation to the parish of New Machar ceased, his memory continues to be revered in that parish even at the present day; and the following anecdote evinces that it is not revered without reason.

A man who, from being in decent circumstances, and a member of the kirk session (See Presbyterians, Encyc.), when Dr Reid was minister, had become, in his old age, poor and infirm, observed to the then minister of the parish, that if he were able to go to Glasgow, and make his case known to his old friend and pastor, he was sure that he would get something done for him. This observation was reported to the Doctor, who instantly recollected the man, though, in all probability, he had not thought of him for thirty years; and he settled upon him an annual pension of ten pounds, which was punctually paid as long as they both lived. The pride of science had not from the mind of this great man eradicated the amiable sympathies of humanity, nor had his philosophic fame made him overlook the unsparing duties of the Christian pastor.

In the year 1751, about the beginning of the session or annual term, one of the professors of philosophy in King's College, Aberdeen, died; and his death being unexpected, presented to the other members of that learned body some difficulty in carrying on the usual course of education for that year. At this our readers will not be surprised, when they reflect on the mode in which science was taught in that university; for he who could with propriety be placed in the vacant chair, must have been qualified, without much previous preparation, to read lectures on Logic, Ontology, Pneumatics, Morals, Politics, Mathematics, and Natural Philosophy (See Gerard, in this Suppl.). In such a place as Aberdeen, it is hardly to be supposed that there was a single man unemployed, to completely master all these branches of science, as to take up the class where it was dropped by the deceased professor, and carry it successfully through that science, whatever it might be, in which, at his death, he chanced to be lecturing. It occurred, however, to the principal, and some of the professors, that the minister of New Machar was fully equal to the task; and the late Dr John Gregory, then professor of medicine, and the Rev. Dr Macleod, the present subprincipal of King's College, were deputed to visit Mr Reid, and request his immediate acceptance of the vacant professorship. He yielded to the request not without some hesitation, and was admitted professor of philosophy on the 22d of November.

He was now in the very situation for which Nature seemed to have intended him. He had not only an opportunity, but it was his duty to cultivate the science to which his attachment was strongest; and the duties of his office made him turn his attention more closely than he had hitherto done to another science, in which he was destined to make a more conspicuous figure than he ever made even in his favorite mathematics.

It was during his professorship in the university of Aberdeen that he wrote his "Essay on Quantity," which was published in the 6th volume of the Philosophical Transactions, and is perhaps the finest specimen of metaphysical mathematics, if we may use such an expression, that is extant in our own or in any other language (See Quantity, Encyc.). It was during the same period that he published his "Inquiry into the Human Mind on the Principles of Common Sense;" a work of unquestionable merit, which has contributed more than any other work whatever to give a rational turn to metaphysical speculations. It was about this period that the degree of D.D. was conferred upon him by his mother college.

The well-earned fame of Dr Reid attracted the attention of the university of Glasgow to him as the fittest person to succeed the celebrated Dr Adam Smith; and he was admitted professor of moral philosophy in that university on the 11th of June 1764. There his attention was not distracted by a multitude of sciences, which it was his duty to teach; and he had leisure to improve his metaphysical system, though he continued through life to amuse himself occasionally with mathematical speculations.

In the year 1773 appeared, in Lord Kames's "Sketches of the History of Man, a brief Account of Aristotle's Logic; with remarks by Dr Reid." It would seem that he had entered upon this talk rather reluctantly, and merely in compliance with the solicitations of his friend, the author of the Sketches. "In attempting (says he) to give some account of the analytics, and of the topics of Aristotle, ingenuity requires me to confess, that though I have often purposed to read the whole with care, and to understand what is intelligible, yet my courage and patience always failed before I had done. Why should I throw away so much time and painful attention upon a thing of so little use? If I had lived in those ages when the knowledge of Aristotle's Organon intitled a man to the highest rank in philosophy, ambition might have induced me to employ upon it some years of painful study; and let, I conceive, would not be sufficient. Such reflections as these always got the better of my resolution, when the first ardour began to cool. All I can say is, that I have read some parts of the different books with care, some slightly, and some perhaps not at all. I have glanced over the whole often; and when any thing attracted my attention, have dipped into it till my appetite was satisfied."

Notwithstanding this modest acknowledgment, we are not sure that any one of Dr Reid's publications does him greater honour than his very perspicuous view of this stupendous system. Having ourselves occasionally looked into the writings of Aristotle, we should not hesitate to say, that it is by much the best analysis of these writings that we have anywhere met with, even though we could not corroborate our own opinion by that of other men much more conversant than we are with the oracular language of the stagyrite. But when it is known that the late Dr Doug of Stirling, to whom Greek was as familiar as his mother tongue, and an equally learned Doctor of Oxford, who has been reading Aristotle ever since he was fourteen years of age, agreed in opinion, that a more accurate view of his logic could not be given in the same compass than had been been given by Dr Reid, we may surely affirm, with some degree of confidence, that this small work adds much to the fame of our celebrated countryman.

Though Dr Reid's health continued good, and his mental faculties unimpaired, till a very short time before his death, he ceased for some years to read lectures from his professorial chair, employing that time in preparations for eternity, and in fitting his lectures for the press. These were published in two volumes; the first in 1785, under the title of "Essays on the Intellectual Powers of Man," dedicated to his friends Dr Gregory and Professor Stewart, both of the university of Edinburgh; and the second in 1788, under the title of "Essays on the Active Powers of Man," without any dedication or preface. He continued to enjoy the same acquirement by this work, as well as the affection of his friends and the reverence of the public, for eight years, dying at Glasgow in the end of September, or the beginning of October 1796, in the 87th year of his age. He had been married, and he left behind him one daughter.

To do justice to the biography of such a man as this, we should here attempt to draw his intellectual character, and to appreciate the merits of his works; but to perform this task in a manner at all worthy of him, or of hope ourselves, would require more room than our limits permit us to allot to any article of the kind; and our readers will be pleased to learn, that they may confidently expect an account of his life, with a critique on his works, by a man better qualified to do justice to both, than the writer of this short sketch pretends to be. His works are in the hands of the speculative public; and by that public will be duly valued, as long as found sense shall be preferred to impious jargon. How long that may be, God only knows; but if anything can guard the minds of our youth against that sophistry of which the object is to attribute real agency to material fluids, and to represent the elective attractions of chemistry as perfectly similar to human volitions, it will be the unstaid study of Dr Reid's "Essays on the Intellectual and Active Powers of Man." They will there find metaphysics divested of mystery, and the profoundest speculations rendered intelligible by the constant use of words in one determined sense. We think, indeed, that in this consists the Doctor's chief merit; for, except when treating of our notions of power, he seems not to have added much to what certainly may be found in the writings of Locke.

Let not our readers suppose, that by this observation we wish to detract in the smallest degree from our author's fame, or to lessen him by comparison with the English philosopher. If on mere topics of speculative science, he appears to us to have thought as Locke thought, it is on the other hand certain, that the greater part of Locke's doctrines may be gleaned from the logical and metaphysical writings of Bacon, Hobbes, and Descartes. Nor need this surprise any one; for he who reflects a moment on the subject, must perceive that such a coincidence of thought in metaphysical science is among men of eminence almost inevitable. Of mind and its powers—the subjects of that science—we neither know nor can know anything, but by patiently attending to the operations of our own minds, when we see, hear, feel, think, reason, and will, &c.; and it is obvious, that every man who is capable of such patient attention, and does not labour under the bias of some prejudice, must view these operations in the same way. The great superiority of Dr Reid over his predecessors, in this department of science, appears to have been this, that he apprehended the operations of his own mind with a clearness, which gave to his language a precision and perspicuity which the language of Locke certainly does not possess.

In the Essay on the Human Understanding, the term idea sometimes signifies a material substance; sometimes the qualities of that substance; sometimes the conception of these qualities; sometimes the power or faculty of the mind by which we conceive a thing; sometimes a perception of sense; and sometimes an intellectual notion. Hence the ambiguity of terms which runs thro' the whole of that immortal work, has furnished both the author's friends and his enemies with an opportunity of attributing to him pernicious doctrines, which we are persuaded he did not maintain, and which, we think, a patient analysis of the essay must convince every man that he did not maintain. From this ambiguity the writings of Dr Reid are perfectly free. His doctrines, whether well or ill-founded, can never be misunderstood by him who is desirous to understand them; and he who knows how much perspicuity of style depends upon accuracy of thinking, will not deem us enemies to his fame for having said that his chief merit consists in the precision of his language.

He has been much censured by some, and much applauded by others, for introducing the phrase common sense into speculative philosophy, as the proper name of that faculty of the mind by which we apprehend first truths; but he is on this account entitled neither to praise nor to censure. He adopted the phrase from others; and has proved, by the most unexceptionable authorities, both ancient and modern, that it may with great propriety be used as he has used it. Whether the adopting of it into works of science was necessary, is another question, on which we have given our opinion elsewhere; it is sufficient in this place to vindicate his use of it, especially in his latter works, from ambiguity.

Candour obliges us to acknowledge, that he has advanced some doctrines which we cannot admit as true. Though not in general partial to Locke, he has adopted his notions respecting our power of abstraction, with hardly any other variation than the substituting of the term conceptions for Locke's favourite phrase ideas. He has likewise endeavoured to prove, that we may distinctly conceive what cannot possibly exist. These mistakes, for such they appear to us, we have pointed out elsewhere (See Metaphysics, Part I. Chap. iii. and iv. Royce); but they are infinitely more than counterbalanced by his clear, accurate, and satisfactory disquisitions on our notions of active power. Had Dr Reid never written a sentence but the essay which treats of this delicate and important subject, he would have been entitled to a place in the very first rank of useful metaphysicians; for, previous to the appearance of his works, we had nothing written directly on power but contradictory and unintelligible jargon. We recommend the serious perusal of this essay, the first in his second volume, to such of our readers as fancy that they distinctly conceive the powers of chemical agents, and that intelligence and volition may result from any mechanical organization.