from Spacetime Physics, p. 5, by Edwin Taylor & John Archibald Wheeler, W.H. Freeman and Company, San Francisco, 1966 edition.
“The principles of special relativity are remarkably simple. They are very much simpler than the axioms of Euclid or the principles of operating an automobile. Yet both Euclid and the automobile have been mastered – perhaps with insufficient surprize – by generations of ordinary people. Some of the best minds of the twentieth century struggled with the concepts of relativity, not because nature is obscure, but simply because man finds it difficult to outgrow established ways of looking at nature. For us the battle has already been won. The concepts of relativity can now be expressed simply enough to make it easy to think correctly – thus “making the bad difficult and the good easy.”[*] The problem of understanding relativity is no longer one of learning but one of intuition – a practiced way of seeing. When seen with this intuition, a remarkable number of otherwise incomprehensible experimental results are revealed to be perfectly natural.”
[*] Quote is from Einstein, in a similar connection, in a letter to the architect Le Corbusier.