The physicist may be satisfied when he has the mathematical scheme and knows how to use for the interpretation of the experiments. But he has to speak about his results also to non-physicists who will not be satisfied unless some explanation is given in plain language. Even for the physicist the description in plain language will be the criterion of the degree of understanding that has been reached.
Werner HeisenbergIf nature leads us to mathematical forms of great simplicity and beauty - by forms I am referring to coherent systems of hypothesis, axioms, etc. - to forms that no one has previously encountered, we cannot help thinking that they are "true," that they reveal a genuine feature of nature... You must have felt this too: The almost frightening simplicity and wholeness of relationships which nature suddenly spreads out before us and for which none of us was in the least prepared.
Werner HeisenbergBy getting to smaller and smaller units, we do not come to fundamental or indivisible units. But we do come to a point where further division has no meaning.
Werner HeisenbergWhenever we proceed from the known to the unkown we may hope to understand, but we may have to learn at the same time a new meaning of the word 'understanding'
Werner Heisenberg