prīmōrdium

1. Initium denotes the beginning in an abstract sense, as the mere point from which a thing begins, in opp. to exitus. Cic. Rosc. Com. 13, 39. Tusc. i. 38. Brut. 34. Sen. Ep. 9. N. Q. iii. 29; whereas principium denotes the beginning as a concrete notion, as that part of the whole which stands before the other parts in things, and goes before them in actions, in opp. to extremum. Cic. Cleunt. 4. Orat. 61, 204. Cæc. 15, 44. In initium the beginning is made only with reference to time; in principium the foundation also is laid with reference to space. The initium is pushed out of the way by that which follows; the principium serves as a basis for that which follows. The initia philosophiæ are the rudiments over which the scholar goes, and which are superseded by further studies; the principia are the fundamental principles, to which he must always recur. Initio usually means “at the beginning, but differently (or, not at all) afterwards;” whereas principio means from the very beginning, and so onwards. 2. Primordium is a more solemn and comprehensive term than principium, and supposes a whole of great extent, the beginning of which is so far removed that one can distinguish a merely apparent beginning from the actual and primeval source and origin. (iii. 163.)