Full Idea
No idea can be properly understood apart from its history.
Gist of Idea
All ideas must be understood historically
Source
Auguste Comte (Intro to Positive Philosophy [1830], Ch.1)
Book Reference
Comte,Auguste: 'Introduction to Positive Philosophy', ed/tr. Ferré,Frederick [Hackett 1988], p.1
A Reaction
This is somewhat dubious. Comte is preparing the ground for asserting positivism by rejecting out-of-date theology and metaphysics. The history is revealing, but can be misleading, when a meaning shifts. Try 'object' in logic.