The rationalists assume that every increase in knowledge and understanding is an advance, a step toward full mental freedom. But this clashes with experience. The people who show themselves, by their behaviour, to be enjoying the experience of freedom, both mental and physical, are not the wise but the ignorant. Those with lifetimes of learning behind them are impressed mainly by the limitations of their knowledge, the ones who are gay, light and free are not the old and learned but the young, and those who enjoy the fullest sense of freedom are the infants who have not yet learnt that they have anything to learn.
Nor is it only subjective feelings that can benefit from ignorance. Lack of knowledge can have objectively useful results. This example is from F. M. Cornford, himself one of the more learned people:
Now suppose that I and the most accomplished geometer in Cambridge… were set in competition to interpret the First Book of Euclid. I would undertake to give a better account of its meaning, just because I know nothing of what Euclid could not have known, whereas in my competitor’s mind every term and proposition would be charged with misleading associations. That instance shows how ignorance of later developments may be a positive advantage. (The Laws of Motion in Ancient Thought Cambridge UP 1931)
from Ideological Commentary 12, August 1984.