What makes a subject difficult to understand — if it is significant, important — is not that some special instruction about abstruse things is necessary to understand it. Rather it is the contrast between the understanding of the subject and what most people want to see. Because of this the very things that are most obvious can become the most difficult to understand. What has to be overcome is not difficulty of the intellect but of the will.
The discovery of truth is prevented more effectively, not by the false appearance things present and which mislead into error, not directly by weakness of the reasoning powers, but by preconceived opinion, by prejudice.
Ludwig Wittgenstein, Philosophical Occasions
Arthur Schopenhauer, Counsels and Maxims