GALILEO: The aim of science is not to open the door to everlasting wisdom, but to set a limit to everlasting error.

[Es ist nicht ihr Ziel, der unendlichen Weisheit eine Tiir zu offnen, sondern eine Grenze zu setzen dem unendlichen Irrtum.]

Bertolt Brecht (1898-1956) German poet, playwright, director, dramaturgist

Life of Galileo [Leben des Galilei], sc. 9 (1940) [tr. Sauerlander/Manheim (1955)]
    (Source)

(Source (German)). Other translations:

It isn't their [the sciences'] job to throw open the door to infinite wisdom but to put a limit to infinite error.
[tr. Willett (1980)]

It is not the aim of science to open a door to infinite wisdom -- but to put an end to infinite error.
[tr. Brenton (1980)]