To ascertain its meaning, it is useless to go to heathen authors.  The Greek philosophers were at variance among themselves.  ARNOBIUS, a Christian writer of the latter part of the third century, in his work Adversus Gentes, speaking of the speculations of the heathen of his day, says :  "In exactly the same way (as the creation and the gods) is the condition of souls discussed.  For this one thinks they are both immortal, and survive the end of our earthly life; that one believes that they do not survive, but perish with the bodies themselves; the opinion of another, however, is that they suffer nothing immediately, but that, after the [form of] man has been laid aside, they are allowed to live a little longer, and then come under the power of death." (*1)

We must therefore, let Scripture be its own interpreter. Psuche exactly corresponds to the Hebrew Nepesh (Ap. 13), as will be seen from the following passages :  Mark 12:29, 30, compared with Deut. 6:4, 5; Acts 2:27 with Ps. 16:10; Rom. 11:3 with 1Kings 19:10; 1Cor. 15:45 with Gen. 2:7.  In all these places, psuche in the New Testament represents nepesh in the Old.

The following are the occurrences of the word :--

1. psuche, used of the lower animals twice, is rendered
   
   1. "life" :  Rev. 8:9
   2. "soul" :  Rev. 16:3
   
   
2. psuche, used of man as an individual (just as we speak of a ship going down with every soul on  board, or of so many lives being lost in a railway accident), occurs 14 times, and is rendered  "soul" :  Acts 2:41, 43; 3:23; 7:14; 27:37.  Rom. 2:9; 13:1.  1Cor. 15:45.  James 5:20.  1Pet.  3:20.  2Pet. 2:14.  Rev. 6:9; 18:13; 20:4.
   
   
3. psuche, used of the life of man, which can be lost, destroyed, saved, laid down, &c., occurs 58  times, and is rendered
   
   1. "life" :  Matt. 2:20; 6:25; 10:39; 16:25; 20:28.  Mark 3:4; 8:35; 10:45.  Luke 6:9; 9:24, 56; 12:23; 14:26; 17:33 (*2).  John 10:11, 15, 17; 12:25; 13:37, 38; 15:13.  Acts 15:26; 20:10, 24; 27:10, 22.  Rom. 11:3; 16:4.  Phil. 2:30.  1John 3:16.  Rev. 12:11.
      
      
   2. "soul" :  Matt. 10:28; 16:26.  Mark 8:36, 37.  Luke 12:20; 21:10.  1Thess. 2:8; 5:23.  Heb. 4:12; 6:19; 10:39; 13:17.  James 1:21.  1Pet. 1:9; 2:11, 25; 4:19.
   
   
4. psuche, used to emphasize the pronoun, as we use "self" (e.g. "my soul" = "myself"), occurs 21  times and is rendered
   
   1. "soul" :  Matt. 11:29; 12:18; 26:38.  Mark 14:34.  Luke 1:46; 12:19.  John 12:27.  Acts 2:27, 31;  14:22; 15:24.  2Cor. 1:23.  Heb. 10:38.  1Pet. 1:22.  2Pet. 2:8.  Rev. 18:14.
   2. "mind" :  Acts 14:2.  Heb. 12:3.
   3. "us" :  John 10:24.
   4. you" :  2Cor. 12:15 (see margin).
   
   
5. psuche, used with intensive force, to express all the powers of one's being, occurs 10 times, and  is rendered
   
   1. "soul" :  Matt. 22:37.  Mark 12:30, 33.  Luke 2:35; 10:27.  Acts 4:32.  3John 2.
   2. "heart" :  Eph. 6:6
   3. "mind" :  Phil. 1:27
   4. "heartily" :  Col. 3:23