"Aehnlich würde jede von vorn herein versuchte Bestimmung des Denkens ausfallen. Man würde es nur durch einen Bezug zu den Dingen erläutern können, welche in dem Denken Grund und Mass finden. Wir begeben uns daher jeder Erklärung, und setzen eine Vorstellung des Denkens und Seins voraus, in der Hoffnung dass beide mit jedem Schritt der Untersuchung sich in sich selbst bestimmen werden." "Indem wir Denken und Sein unterscheiden, fragen wir, wie ist es möglich, dass sich im Erkennen Denken und Sein vereinigt? _Diese Vereinigung sprechen wir vorläufig als eine Thatsache aus, die das Theoretische wie das Praktische beherrscht._" Trendelenburg, Logische Untersuchungen, sect. 3, pp. 103-104, Berlin, 1840.] [Side-note: Object always relative to Subject--Either without the other, impossible. Plato admits this in Sophistes.] I cannot therefore agree with Plato in regarding the Protagorean doctrine--Homo Mensura--as having any dependance upon, or any necessary connection with, the other theory (canvassed in the Theætêtus) which pronounces cognition to be sensible perception. Objects of thought exist in relation to a thinking Subject; as Objects of sight or touch exist in relation to a seeing or touching Subject. And this we shall find Plato himself declaring in the Sophistes (where his Eleatic disputant is introduced as impugning a doctrine substantially the same as that of Plato himself in the Phædon, Timæus, and elsewhere) as well as here in the Theætêtus. In the Sophistes, certain philosophers (called the Friends of Forms or Ideas) are noticed, who admitted that all sensible or perceivable existence ([Greek: ge/nesis]--Fientia) was relative to a (capable) sentient or percipient--but denied the relativity of Ideas, and maintained that Ideas, Concepts, Intelligible Entia, were not relative but absolute. The Eleate combats these philosophers, and establishes against them--That the Cogitable or Intelligible existence, Ens Rationis, was just as much relative to an Intelligent or Cogitant subject, as perceivable existence was relative to a Subject capable of perceiving--That Existence, under both varieties, was nothing more than a potentiality, correlating with a counter-potentiality ([Greek: to\ gnôsto\n] with [Greek: to\ gnôstiko/n], [Greek: to\ ai)sthêto\n] with [Greek: to\ ai)sthêtiko/n], and never realised except in implication therewith.[27] [Footnote 27: Plato, Sophistes, pp. 247-248. The view taken of this matter by Mr. John Stuart Mill, in the third chapter of the first Book of his System of Logic, is very instructive; see especially pp. 65-66 (ed. 4th).