Some atoms, indeed, were “unsociable,” having no means of mutual attachment; hence their combination was effected by enclosing them in a shell formed by the “social” particles. Some atoms had means for attachment at two points, which accounts, in part, for the greater or less mobility of the various atoms. The soul consists of the finest and smoothest atoms, akin to those of fire; and since they penetrate the whole body, their motions give rise to the phenomena of life. All objects project into space images of themselves, composed of atoms, which strike against the senses, and are perceived by similar atoms--“like atoms are perceived by like.” These assumptions were wholly unacceptable to the critical mind of Aristotle,[18] as well as to his distinguished disciple, Strato of Lampsacus, teacher of Ptolemy Philadelphus. The Roman Stoic, Cicero, regarded the Democritean theory of cohesion and compounding of substances as wholly fantastic.[19] Yet the critics of Democritus had no better theory to offer in its place, since they, like the Atomists themselves, had no conception of the electrical, chemical or gravitational attraction of bodies for each other, or of the fact that the pressure of the atmosphere causes the ascent of fire, vapor and heated molecules in general. To the foregoing objections, others might be offered, but we add only that in modern terms, the impact of indivisible and indeformable atoms upon one another could not produce the required movement of elementary masses. For “if the atoms are rigid, transmission of motion through impact is impossible; if they are elastic, they are then deformable and composed of parts, which is contrary to the hypothesis and implies forces of cohesion and elasticity.”[20] Democritus, though he was the greatest physicist of his age, could not, of course, be expected to anticipate our modern objections to his doctrine--or his master’s doctrine. The immortal Newton (1642-1727) himself, even Dalton (1766-1844), founder of the modern chemical atomic theory (as distinguished from the _physical_ atomic theories of his predecessors), could not anticipate the advances that have made possible the relentless criticism of modern physics and chemistry. Newton, Boyle and Huygens had no idea that the “atoms” of their conceptions were occupied mostly by “empty space” (using this phrase in its popular meaning--modern science recognizing no actually empty space: for all space contains a gravitational “ether” if not an electromagnetic field of energy).