The most accurate definition of what an I is can be found in Richard of St. Victor: Dicatur itaque a Daniele Danielitas, sicut ab homine humanitas. Danielitas itaque intelligatur illa substantialitas, vel, si magis placet, illa subsistentia ex qua Daniel esse habet illa substantia quae ipse est et quam participare non potest aliqua alia. Humanitas itaque, sicut corporalitas, est multis communis. Danielitas vero omnino incommunicabilis. Richardus a S. Victore, De Trinitate II, c. 12 “Therefore, let ‘Danielity’ be named from Daniel, just as ‘humanity’ is named from a human being. Accordingly, ‘Danielity’ should be understood as that substantiality — or, if one prefers, that subsistence — by which Daniel has being: that very substance which he himself is and which no other can share. ‘Humanity,’ however, like ‘corporeality,’ is common to many; but ‘Danielity’ is entirely incommunicable.” The individual is constituted by a subsistentia that gives him that substance which he himself i...
This is perhaps the most profound description of the Heraclitean Logos: अनिरोधमनुत्पादमनुच्छेदमशाश्वतम्। अनेकार्थमनानार्थमनागममनिर्गमम्॥ anirodham anutpādam anucchedam aśāśvatam anekārtham anānārtham anāgamam anirgamaṁ (Nāgārjuna, Mūlamadhyamakakārikā 1.1) अशाश्वतम् (aśāśvatam) — “not eternal”: not because it is merely temporal, but because it makes itself intelligible through its presence within human time. Neither perishing nor arising in time; neither terminable nor eternal; neither self-identical nor changing in form; neither coming nor going. (Sprung’s translation) It is nothing more than a σύλληψις - a seizing, grasping, or apprehension - which not everyone can develop into genuine knowledge. Within this σύλληψις , the Logos is always turned towards individuals; yet only some individuals are turned towards the Logos.