Full Idea
The scientific search is for such classification as will make it possible to correlate appearance and behaviour, to discover law, to penetrate to the "essential nature" of things in order that behaviour may become predictable.
Gist of Idea
Science seeks classification which will discover laws, essences, and predictions
Source
C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.368)
Book Reference
Peirce,James,Dewey etc: 'Pragmatism - The Classic Writings', ed/tr. Thayer,H.S. [Hackett 1982], p.368
A Reaction
Modern scientific essentialists no longer invoke scare quotes, and I think we should talk of the search for the 'mechanisms' which explain behaviour, but Lewis seems to have been sixty years ahead of his time.