Dr Thomas, a distinguished philosopher, and in some measure the founder of a school, was the son of Lewis Reid, minister of the parish of Strachan, in the county of Kincardine, Scotland. His mother, the daughter of Mr Gregory of Kinnaidrie, in Banffshire, was one of twenty-nine children, and sister to David, James, and Charles Gregory, who were at the same period professors of astronomy or mathematics in the universities of Oxford, Edinburgh, and St Andrews.

Dr Reid was born at the parsonage-house of Strachan in April 1710, and received the elementary parts of his education at the parish-school of Kincardine O'Neil. The parochial schools of Scotland are said to have been much superior at that period to what they are at present, and young men went from them well furnished with philosophical learning to the different universities. The early progress of young Reid must have been very extraordinary, since he was qualified to profit by the lectures of the professors at the age of twelve. He soon gave very striking proofs that he inherited the genius of his mother's family, and was conspicuous amongst the students of mathematics, in a college where that science has always been cultivated with zeal and success. He continued longer at the university than the usual term of years, having been appointed to the office of librarian, a situation which was every way agreeable to him, as it gave him ample opportunities of gratifying his passion for study. About this time he became intimately attached to John Stewart, afterwards professor of mathematics in Marischal College, a connection which greatly strengthened his predilection for mathematical studies.

He resigned the office of librarian in the year 1736, and accompanied Mr Stewart to England, when they paid a visit to London, Oxford, and Cambridge, and were introduced to several persons of the first literary distinction. On account of his relation to Dr David Gregory, he had ready access to the celebrated Martin Folkes, whose house might be said to contain many of the most interesting objects to be met with in the metropolis. He saw Dr Bentley at Cambridge, with whose erudition he was much delighted, as well as amused with his vanity; and he also conversed frequently with Saunderson, the blind mathematician. Dr Reid in his philosophical speculations refers to this gentleman's blindness, as a singular phenomenon in the history of the human mind.

Dr Reid maintained an uninterrupted friendship with the learned and amiable Mr Stewart until the year 1766, at which time the latter was carried off by a malignant fever. The circumstances attending the death of this excellent man deeply wounded the sensibility of Dr Reid; for his wife and daughter were carried off by the same disorder, and buried with him in the same grave.

The King's College of Aberdeen presented Dr Reid to the living of New Machar in the year 1737; but such was the zeal of the people against the law of patronage at that time, that he not only met with violent opposition, but was also exposed to personal danger. But his attention to the duties of his office was so exemplary, his temper so mild and forbearing, and his spirit of humanity so active, that in a short time he subdued their prejudices; and when at last called in the course of Providence to a different situation, the very people who had been guilty of gross and indecent outrages against him followed him, on his departure, with their benedictions and tears.

In the year 1740, he married Elizabeth, daughter of his uncle, Dr George Reid, physician in London, after which his popularity at New Machar very much increased. Her manners were so accommodating, and so numerous were her kind offices to the sick and the indigent, that the departure of the family from the neighbourhood was looked upon as a general misfortune. The manner in which several old men were accustomed to speak upon the subject is worthy of being kept in remembrance. "We fought," said they, "against Dr Reid when he came, and we would have fought for him when he went away."

The greater part of his time during his residence at New Machar was devoted to the most intense study, particularly directing his attention to the laws of external perception, and of the other principles which constitute the basis of human knowledge. He unbended his mind by the amusements of gardening and botany, of which he was extremely fond, even in old age.

The professors of King's College, in the year 1752, made choice of Dr Reid to be professor of philosophy, originating wholly from the high opinion they were led to entertain of his talents and erudition. We are not acquainted with the particular plan which he adopted and pursued in the course of his lectures; but his department at that period comprehended mathematics and physic, logic and... ethics; a practice then followed in the other universities of Scotland, instead of appointing a professor for each distinct branch.

Dr Reid had not been long in Aberdeen, till, in conjunction with Dr John Gregory, he projected a literary society, which continued for a number of years, and met once a week. The writings of Reid, Gregory, Campbell, Beattie, and Gerard, evince the numerous advantages which the members derived from this institution, as they were in the habit of subjecting such works as they intended for publication, to the test of friendly criticism.

It is perhaps not too much to assert, that of all the publications which appeared about this time, the Inquiry into the Human Mind by Dr Reid discovered by far the greatest originality and profound thinking. It appears that he had conceived the plan, and deeply meditated upon it, long before its publication; yet, without the applause of his literary associates, it is more than probable that his native modesty would have prevented him from giving it to the world.

The publication of Mr Hume's Treatise of Human Nature, in 1739, led him to question the principles commonly received with regard to the human understanding. He admitted, when a youth, but without any attentive examination, the opinions on which Mr Hume's scepticism was raised; but when he carefully adverted to the consequences which these principles appeared to involve, he instantly began to suspect their truth. To subvert the sceptical theory of Mr Hume was the grand object of Dr Reid's Inquiry, which he submitted to the examination of Mr Hume himself. That philosopher, even after he had seen some parts of the work, discovers not a little of the Jewish spirit of unbelief that any good thing should come out of Nazareth; and considering his antagonist as a clergyman, and belonging to an order of men from whom prejudice would not allow him to expect any soundness of reasoning in matters of science, he betrays more than want of good humour, as Dr Reid's biographer expresses himself, when he says, in no very courteous language, in a letter to Dr Blair, "I wish that the persons would confine themselves to their old occupation of worrying one another, and leave philosophers to argue with temper, moderation, and good manners." But though Mr Hume, as appears from the words just quoted, was very angry that a clergyman should become a philosopher, on a second perusal of the Inquiry, he seems to have held very different sentiments, when he wrote to the author himself in the following terms. "By Dr Butler's means, I have been favoured with the perusal of your performance, which I have read with great pleasure and attention. It is certainly very rare, that a piece so deeply philosophical is wrote [written] with so much spirit, and affords so much entertainment to the reader; though I must still regret the disadvantages under which I read it, as I never had the whole performance at once before me, and could not be able fully to compare one part with another. To this reason, chiefly, I ascribe some obscurities, which, in spite of your short analysis or abstract, still seem to hang over your system. For I must do you the justice to own, that when I entered into your ideas, no man appears to express himself with greater perspicuity than you do; a talent which, above all others, is requisite in that species of literature which you have cultivated....As I was desirous to be of some use to you, I kept a watchful eye all along over your style; but it is really so correct, and so good English, that I found not anything worth remarking. There is only one passage in this chapter, where you make use of the phrase hinder to do instead of hinder from doing, which is the English one; but I could not find the passage when I sought for it. You may judge how unexceptionable the whole appeared to me, when I could remark so small a blemish."

The impression made on the minds of speculative men by the publication of Dr Reid's Inquiry was as great as could reasonably be expected from the nature of his undertaking. It was not level to the comprehension of the multitude, nor even addressed to them; and as it examined opinions with the utmost freedom which had obtained the sanction of the highest authorities, it had little prospect of conciliating the favour of the learned. Some, however, there were, who perceived the extent of his views, and beheld in his pages the true spirit and language of inductive investigation, which made proselytes of many, who, again, warmly recommended the work to the attention of others. The Inquiry of Dr Reid was so much esteemed by the learned body of teachers then in the University of Glasgow, that they gave him an invitation to the vacant professorship of moral philosophy in the year 1763. It was no doubt with a considerable degree of reluctance that he resolved to leave Aberdeen; yet so numerous were the allurements which Glasgow presented to a man of his extensive erudition and deep research, that he gave it the preference. That seminary of learning could then boast of a Moor, a Simpson, a Black, a Leechman, the two Wilsons, father and son, and the acute, discriminating Millar, with all of whom he was more or less intimate, and whose fascinating conversation made him in some measure forget that he had long been acquainted with men of genius in the university of Aberdeen.

Dr Reid's merit as a public teacher arose principally from that fund of original philosophy which is characteristic of his writings, and from his invincible patience and perseverance in recommending such principles as he conceived to be of the last importance to human happiness. His style, too, was simple and perspicuous; his character was grave and possessed of authority; and his students felt such an interest in the doctrines which he inculcated, that he never failed to be heard with the most profound attention.

In the year 1773 his remarks on Aristotle's logic appeared in Lord Kames's Sketches of the History of Man. "In attempting," says he, "to give some account of the Analytics and of the Topics of Aristotle, ingenuity [ingeniousness] obliges 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 entitled a man to the highest rank in philosophy, ambition might have induced me to employ upon it some years of painful study; and less, 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 part 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."

But, in spite of his modest declarations, it is matter of doubt with some, whether any of his publications does him more honour than his perspicuous view of this complicated system. It is unquestionably superior to any other analysis of these writings that we have yet seen; an opinion amply confirmed by the sentiments of different literary characters who were intimately acquainted with the works of the great philosopher of antiquity.

Dr Reid declined reading lectures in the university for some years before his death; and he devoted this period to the task of preparing for the press his great work, which was published in two volumes 4to, the first in 1785, entitled Essays on the Intellectual Powers of Man; and the second in 1788, entitled Essays on the Active Powers of