What psychologists do believe is that all of us live much of our life guided by the impressions of System 1 — and we often do not know the source of these impressions. How do you know that a statement is true? If it is strongly linked by logic or association to other beliefs or preferences you hold, or comes from a source you trust and like, you will feel a sense of cognitive ease. The trouble is that there may be other causes for your feeling of ease — including the quality of the font and the appealing rhythm of the prose — and you have no simple way of tracing your feelings to their source.

— Thinking, Fast and Slow by Daniel Kahneman