The most precise and complete formulation of the law of higher logic I find in the writing of Plotinus, in his On Intelligible Beauty. I shall quote this passage in the succeeding chapter.
I have called this system of higher logic Tertium Organum because for us it is the third canon — third instrument — of thought after those of Aristotle and Bacon. The first was Organon, the second, Novum Organum. But the third existed earlier than the first.
Man, master of this instrument, of this key, may open the door of the world of causes without fear.

Ch. XXI - Tertium Organum (1912; 1922)