Sirach 16:23

23 He that wanteth understanding will think upon vain things: and a foolish man erring imagineth follies.

Sirach 16:23 In-Context

21 It is a tempest which no man can see: for the most part of his works are hid.
22 Who can declare the works of his justice? or who can endure them? for his covenant is afar off, and the trial of all things is in the end.
23 He that wanteth understanding will think upon vain things: and a foolish man erring imagineth follies.
24 My son, hearken unto me, and learn knowledge, and mark my words with thy heart.
25 I will shew forth doctrine in weight, and declare his knowledge exactly.

The Brenton translation of the Septuagint is in the public domain.