[115] Histoire des Mathématiques, vol. i. p. 97. [116] De vi Percussionis, Bononiæ, 1667. [117] Mec. Analyt. [118] Mechanica. [119] Diog. Laert. In vit. Archyt. [120] De Cœlo, lib. i. c. 1. [121] Phys. lib. i. c. 3. [122] Lib. iii. c. 2. The Aristotelians distinguished between things as existing in act or energy (ενεργεια) and things in capacity or power (δυναμις). For the advantage of those who may think the distinction worth attending to, we give an illustration of Aristotle's meaning, from a very acute and learned commentator:—"It (motion) is something more than dead capacity; something less than perfect actuality; capacity roused, and striving to quit its latent character; not the capable brass, nor yet the actual statue, but the capacity in energy; that is to say, the brass in fusion while it is becoming the statue and is not yet become."—"The bow moves not because it may be bent, nor because it is bent; but the motion lies between; lies in an imperfect and obscure union of the two together; is the actuality (if I may so say) even of capacity itself: imperfect and obscure, because such is capacity to which it belongs."—Harris, Philosophical Arrangements. [123] Lib. iv. c. 1. [124] Lib. iv. c. 11. [125] De Cœlo, lib. i. c. 2. [126] Phys. lib. vii. c. 8. [127] De Cœlo, lib. i. c. 6. [128] Phys. lib. vii. c. 2. [129] Mechanica. [130] Εαν δε εν μηδενι λογῳ φερηται δυο φορας κατα μηδενα χρονον, αδυνατον ευθειαν ειναι την φοραν. Εαν γαρ τινα λογον ενεχθῃ εν χρονῳ τινι τουτον αναγκη τον χρονον ευθειαν ειναι φοραν δια τα προειρημενα, ὡστε περιφερες γινεται δυο φερομενον φορας εν μηδενι λογῳ μηδενα χρονον.—_i.e._ v = ds/dt [131] De Cœlo, lib. i. c. 3. [132] Lib. iv. c. 2. [133] Phys., lib. iv. c. 8. [134] De Proport. Basileæ, 1570. [135]