“In many cases, ignorance is a good thing : the mind retains its freedom of investigation and does not stray along roads that lead nowhither, suggested by one's reading. I have experienced this once again. … Yes, ignorance can have its advantages; the new is found far from the beaten track.”

Directives on the Cultural Revolution (1966-1972)

Rich Dad Poor Dad: What the Rich Teach Their Kids About Money-That the Poor and the Middle Class Do Not!

Source: Think Big (1996), p. 22

This or similar statements are more often misattributed to Herbert Spencer, but the source of the phrase "contempt prior to investigation" seems to have been William Paley, A View of the Evidences of Christianity (1794): "The infidelity of the Gentile world, and that more especially of men of rank and learning in it, is resolved into a principle which, in my judgment, will account for the inefficacy of any argument, or any evidence whatever, viz. contempt prior to examination."
Misattributed

Source: Sacré Bleu: A Comedy d'Art

History of My Life (trans. Trask 1967), 1997 reprint, Preface, p. 34
Referenced

A Treasury of Inspirational Thoughts (2004) by S.P. Sharma, p. 41.
Disputed

"The Death of Me", p. 150
Awareness (1992)
Context: Can one be fully human without experiencing tragedy? The only tragedy there is in the world is ignorance; all evil comes from that. The only tragedy there is in the world is unwakefulness and unawareness. From them comes fear, and from fear comes comes everything else, but death is not a tragedy at all. Dying is wonderful; it's only horrible to people who have never understood life. It's only when you're afraid of life that you fear death. It's only dead people who fear death.

77.
On the Special Laws