“Ignorance is not a simple lack of knowledge but an active aversion to knowledge, the refusal to know, issuing from cowardice, pride or laziness of mind.”

1 Corinthians 8:1
Source: Holy Hesychia: The Stillness that Knows God, p. 33

Source: Treatise Concerning Eternal and Immutable Morality (1731), Ch. 1, sct. 1

The Interpretation of Dreams (1900), from The Standard Edition of the Complete Psychological Works of Sigmund Freud, translated by James Strachey.
At any rate the interpretation of dreams is the via regia to a knowledge of the unconscious in the psychic life.
Alternate translation by Abraham Arden Brill, p. 483 http://books.google.com/books?id=OSYJAAAAIAAJ&pg=PA483#v=onepage&q&f=false. Freud did use the Latin phrase via regia in the original as opposed to translating it into the German of the surrounding text.
"Royal road" or via regia is an allusion to a statement attributed to Euclid.
1900s

On Practice (1937)

Source: In Praise of Philosophy (1963), p. 5
Context: Even those who have desired to work out a completely positive philosophy have been philosophers only to the extent that, at the same time, they have refused the right to install themselves in absolute knowledge. They taught not this knowledge, but its becoming in us, not the absolute but, at most, our absolute relation to it, as Kierkegaard said. What makes a philosopher is the movement which leads back without ceasing from knowledge to ignorance, from ignorance to knowledge, and a kind of rest in this movement.

La plupart des évènements ont des causes aussi petites. Nous les ignorons, parce que la plupart des historiens les ont ignorées eux-mêmes, ou parce qu’ils n’ont pas eu d’yeux pour les appercevoir. Il est vrai qu’à cet égard l’esprit peut réparer leurs omissions : la connoissance de certains principes supplée facilement à la connoissance de certains faits.
Essay III, Chapter I
De l'esprit or, Essays on the Mind, and Its Several Faculties (1758)

Concluding Paragraph
On Practice (1937)
Original: (zh-CN) 通过实践而发现真理，又通过实践而证实真理和发展真理。从感性认识而能动地发展到理性认识，又从理性认识而能动地指导革命实践，改造主观世界和客观世界。实践、认识、再实践、再认识，这种形式，循环往复以至无穷，而实践和认识之每一循环的内容，都比较地进到了高一级的程度。这就是辩证唯物论的全部认识论，这就是辩证唯物论的知行统一观。