“Emperors are vain and useless things.”

Source: The Picture of Dorian Gray

The Works of Ben Jonson, Second Folio (1640), Timber: or Discoveries

Source: The Picture of Dorian Gray

A Few Maxims for the Instruction of the Over-Educated (1894)

Source: Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter LXXXVIII: On liberal and vocational studies, Line 45.

Misattributed
Source: Seneca, Epistle 88, as seen in the following: "You may sweep all these theories in with the superfluous troops of 'liberal' studies; the one class of men give me a knowledge that will be of no use to me, the other class do away with any hope of attaining knowledge. It is better, of course, to know useless things than to know nothing. One set of philosophers offers no light by which I may direct my gaze toward the truth; the other digs out my very eyes and leaves me blind." Seneca: Epistle 88 http://www.stoics.com/seneca_epistles_book_2.html#%E2%80%98LXXXVIII1

Arithmetica Universalis (1707), p.248

Also misattributed to John Steinbeck.
Source: The Works of John Ruskin: The stones of Venice, v. 1-3