ITS TECHNICAL FORMS. 59 



body; it is, however, impossible that two bodies 

 should exist in the same place, so that it is not a 

 body;" and this reasoning appears to leave him 

 more satisfied with his doctrine, that Light is an 

 Energy or Act. 



But we have a more distinctly technical form 

 given to this notion. Aristotle introduced a word 

 formed by himself, to express the act which is thus 

 opposed to inactive power: this is the celebrated 

 \vord eWeXe'^eta. Thus the noted definition of Mo- 

 tion in the third book of the Physics 20 , is that it is 

 "the Entelechy, or Act, of a moveable body in 

 respect of being moveable ;" and the definition of 

 the Soul is 21 that it is "the Entelechy of a natural 

 body which has life by reason of its power." This 

 word has been variously translated by the followers 

 of Aristotle, and some of them have declared it 

 imtranslateable. Act and Action are held to be 

 inadequate substitutes; the very act, ipse cursus 

 actionis is employed by some ; primus actus is 

 employed by many, but another school use pri- 

 nuift actus of a non-operating form. Buda3us uses 

 efficacia. Cicero 22 translates it "quasi quandam 

 continuatam motionem, et perennem ;" but this pa- 

 raphrase, though it may fall in with the description 

 of the soul, which is the subject with which Cicero 

 is concerned, does not appear to agree with the 

 general applications of the term. Hermolaus Bar- 

 barus is said to have been so much oppressed with 



20 Phys. iii. 1. 2I De Anima. ii. 1. 22 Tusc. i. 10. 



