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222 intelligence, to be a first cause, (as Empedocles made affinity to be an element,) to be innate in and the source of motion in animals, as well as the cause, in nature, of the universe and its order.

Note 11, p. 24. Thales, too, from what, &c.] In this allusion to the influence of the magnet, Thales may have been criticising the opinions which made motion upon life. He was the founder of the school which derived all things from one or more material and indestructible elements; he believed water to be the sole element, (whence he demonstrated that the earth is from water), and was probably led, Aristotle observes, to this conception, from perceiving that the nutrition of all creatures is fluid; that heat is produced from water, and that by heat animals live; and, then, that all seminal particles are naturally fluid.

Note 12, p. 24. Diogenes, together with some other writers, &c.] It is probable that this opinion was suggested to Diogenes by the respiration, which he knew to be essential to animal existence and dependent upon the air; although the process itself, and the changes effected by it, were of course then unknown. Air,, was believed to be necessary for the maintenance of life, and so it might well be regarded as the originating cause of all things; and more especially by one who saw so far, as was shewn in a former note, into its mode of agency. It is shewn by Aristotle that he had well