EXPERIMENTAL PHILOSOPHY;

That philosophy which proceeds on experiments, which deduces the laws of nature, and the properties and powers of bodies, and their actions upon each other, from sensible experiments and observations.

I. It is not very long since this science has been known to the world, or, to speak more properly, since it was first reduced into a system. Natural philosophy has been, for these 50 centuries, nothing more than a confused heap of systems laid one upon another, and very frequently the one clashing against the other. Each philosopher thought, that he had an equal right to erect a similar edifice to his own memory. They adopted barbarous terms and expressions, that conveyed confused ideas only. For explications, they gave certain unintelligible or unmeaning words, which had been introduced by the authority of some celebrated name, but from which a man of understanding could not receive the least information. At length, the true physics was brought to light; it was drawn from the obscurity of the schools, where it had grown old under the authority of Aristotle, and scarce anything been suffered to remain of it but the name. This reformation proceeded principally from the manner of studying it. Instead of guessing at it, they began to investigate it by experiments; and whereas they formerly confined themselves to speculations, and vague researches concerning phenomena and their causes, that were always merely conjectural, they now gave ocular demonstrations of causes and effects by means of experiments; and this is what they call experimental philosophy.

II. The principles of this philosophy are as follow. All the material substances, whose assemblage composes the universe, are called natural bodies. What we perceive in these substances that is uniform and inviolable, and of which we do not know the cause, is called their properties. Physics sets out with this, as from a fixed point, in order to explain the different phenomena that are perceived on the earth, in the water, the air, or fire, and in all that these elements contain. For though it does not pretend to know all that bodies have in common among themselves, or all that is peculiar to each one of them; yet it knows a certain number of their properties, which it regards as primary, till it discovers a precedent cause of which they may be the effects; and which properties are general, and in a manner inseparable from all matter, as for example, extension. There are likewise properties of an inferior order, which do not appertain to all bodies but as they are in certain states, or under certain circumstances; these, in general, are nothing more than combinations of the primary properties; and form a second class, as for example, fluidity. Lastly, these properties of the first and second order combine more and more, and become common to a still smaller number of bodies; and here they are no longer extended to all bodies, as the first; nor are peculiar to certain states, as the second; but are confined to genders, species, or even individuals. Such are several properties of the air, fire, light, metals, the magnet, &c. These three orders of properties are the subject of the inquiries of experimental philosophy, which proves by experiments those that are already known, and frequently discovers others that were unknown.