Anna Karenina by Part 8 Chapter 10 Page 8

Whether he were acting rightly or wrongly he did not know, and far from trying to prove that he was, nowadays he avoided all thought or talk about it.

Reasoning had brought him to doubt, and prevented him from seeing what he ought to do and what he ought not. When he did not think, but simply lived, he was continually aware of the presence of an infallible judge in his soul, determining which of two possible courses of action was the better and which was the worse, and as soon as he did not act rightly, he was at once aware of it.

So he lived, not knowing and not seeing any chance of knowing what he was and what he was living for, and harassed at this lack of knowledge to such a point that he was afraid of suicide, and yet firmly laying down his own individual definite path in life.