(source) 
Eugene Paul Wigner
(17 Nov 1902  1 Jan 1995)

Science Quotes by Eugene Paul Wigner (15 quotes)
[F. Werner, while a student in Princeton,] came to me and expressed his bewilderment with the fact that we make a rather narrow selection when choosing the data on which we test our theories. “How do we know that, if we made a theory which focuses its attention on phenomena we disregard and disregards some of the phenomena now commanding our attention, that we could not build another theory which has little in common with the present one but which, nevertheless, explains just as many phenomena as the present theory?” It has to be admitted that we have no definite evidence that there is no such theory.
— Eugene Paul Wigner
[T]he laws of quantum mechanics itself cannot be formulated … without recourse to the concept of consciousness.
— Eugene Paul Wigner
I believe that the present laws of physics are at least incomplete without a translation into terms of mental phenomena.
— Eugene Paul Wigner
If we had a complete knowledge of all events in the world, everywhere and at all times, there would be no use for the laws of physics, or, in fact, of any other science. … They might give us a certain pleasure and perhaps amazement to contemplate, even though they would not furnish new information.
— Eugene Paul Wigner
It is, as Schrödinger has remarked, a miracle that in spite of the baffling complexity of the world, certain regularities in the events could be discovered. One such regularity, discovered by Galileo, is that two rocks, dropped at the same time from the same height, reach the ground at the same time. The laws of nature are concerned with such regularities.
— Eugene Paul Wigner
Mathematics is the science of skillful operations with concepts and rules invented just for this purpose.
— Eugene Paul Wigner
Nothing in our experience suggests the introduction of [complex numbers]. Indeed, if a mathematician is asked to justify his interest in complex numbers, he will point, with some indignation, to the many beautiful theorems in the theory of equations, of power series, and of analytic functions in general, which owe their origin to the introduction of complex numbers. The mathematician is not willing to give up his interest in these most beautiful accomplishments of his genius.
— Eugene Paul Wigner
Physics does not endeavour to explain nature. In fact, the great success of physics is due to a restriction of its objectives: it only endeavours to explain the regularities in the behavior of objects.
— Eugene Paul Wigner
Physics is becoming so unbelievably complex that it is taking longer and longer to train a physicist. It is taking so long, in fact, to train a physicist to the place where he understands the nature of physical problems that he is already too old to solve them.
— Eugene Paul Wigner
The great mathematician fully, almost ruthlessly, exploits the domain of permissible reasoning and skirts the impermissible. … [I]t is hard to believe that our reasoning power was brought, by Darwin’s process of natural selection, to the perfection which it seems to possess.
— Eugene Paul Wigner
The mathematical formulation of the physicist’s often crude experience leads in an uncanny number of cases to an amazingly accurate description of a large class of phenomena. This shows that the mathematical language has more to commend it than being the only language which we can speak; it shows that it is, in a very real sense, the correct language.
— Eugene Paul Wigner
The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve.
— Eugene Paul Wigner
The unreasonable efficiency of mathematics in science is a gift we neither understand nor deserve.
— Eugene Paul Wigner
The world is very complicated and it is clearly impossible for the human mind to understand it completely. Man has therefore devised an artifice which permits the complicated nature of the world to be blamed on something which is called accidental and thus permits him to abstract a domain in which simple laws can be found.
— Eugene Paul Wigner
With thermodynamics, one can calculate almost everything crudely; with kinetic theory, one can calculate fewer things, but more accurately; and with statistical mechanics, one can calculate almost nothing exactly.
— Eugene Paul Wigner
See also:
 17 Nov  short biography, births, deaths and events on date of Wigner's birth.
 The Recollections of Eugene P. Wigner, by Eugene Paul Wigner, Andrew Szanton.  book suggestion.