ATOM, ἄτομος, in Philosophy, a Corpuscle; or a Part or Particle of Matter so minute as to be indivisible. See CORPUSCLE. The Word is Greek, ἄτομος; formed of the privative ἀ, and τέμνω, I cut, I divide.
Atoms are properly the minima naturae, the last or ultimate particles into which bodies are divisible; and are conceived as the first rudiments, or component parts of all physical magnitude, or the pre-existent and incorruptible matter whereof bodies were formed. See PARTICLE, BODY, etc.
The notion of atoms arises hence, that matter is not divisible in infinitum. See DIVISIBILITY. And hence many authors are led to deny the reality of atoms, together with that of mathematical points: An atom, say they, either has parts, or it has none: If it has none, it is a mere mathematical point: If it has, then do these parts also consist of others, and so to infinity. See CONTINUITY. But this is to recede from the genuine character of atoms; which are not esteemed indivisible, because of their want of bigness, or parts; (for all physical magnitude must have three dimensions, length, breadth, and thickness; and all extension is divisible) but they are indivisible on account of their solidity, hardness, and impenetrability, which preclude all division, and leave no vacancy for the admission of any foreign force to separate or disunite them. See IMPENETRABILITY, DIVISIBILITY, EXTENSION, MATTER, etc.
As atoms are the first matter, 'tis necessary they should be indissoluble, in order to their being incorruptible.—Sir Isaac Newton adds, that 'tis also required they be immutable, in order to the world's continuing in the same state, and bodies being of the same nature now as formerly. See HARDNESS.
Hence the ancients were also led to maintain atoms, eternal; for that what is immutable must be eternal. See ETERNITY. They also added gravity, and in consequence thereof, motion, to their atoms: And further, observing that atoms thus falling perpendicularly, could not join or unite together, they super-added a fortuitous or side motion, and furnished them with certain hooked parts, in order to enable them to catch and hang the better together.—And from a casual or fortuitous jumble of these hooked atoms, they supposed the whole universe to be formed. See GRAVITY, MOTION, HOOKED, etc.
