“It is better to teach a few things perfectly than many things indifferently, and an overloaded curriculum is useless. The object of instruction is not to produce technicians, but good active minds.”

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

Sec. 82
Some Thoughts Concerning Education (1693)

Source: Marina

Source: Household Papers and Stories (1864), Ch. 10.

Referring to his rival Raymond Poincaré, as quoted in Paris 1919 : Six Months That Changed the World (2003) by Margaret MacMillan, p. 33

Source: The 80/20 principle: the secret of achieving more with less (1999), p. 142

§ 5
From Lives and Opinions of the Eminent Philosophers by Diogenes Laërtius

The Paris Review interview
Context: Many writers write a great deal, but very few write more than a very little of the real thing. So most writing must be displaced activity. When cockerels confront each other and daren’t fight, they busily start pecking imaginary grains off to the side. That’s displaced activity. Much of what we do at any level is a bit like that, I fancy. But hard to know which is which. On the other hand, the machinery has to be kept running. The big problem for those who write verse is keeping the machine running without simply exercising evasion of the real confrontation. If Ulanova, the ballerina, missed one day of practice, she couldn’t get back to peak fitness without a week of hard work. Dickens said the same about his writing—if he missed a day he needed a week of hard slog to get back into the flow.