"Only when they must choose between competing theories do scientists behave like philosophers." Thomas Kuhn, born 18 July 1922.
"Nature always uses the simplest means to accomplish its effects." Pierre Louis Moreau de Maupertuis, born 17 July 1698.
"How quick are we to learn, that is, to imitate what others have done or thought before. And how slow to understand, that is, to see the deeper connections. Slowest of all, however, are we in inventing new connections or even applying old ideas in a new field." Frits Zernike, born 16 July 1888.
"We can start measuring only when we know what to measure: qualitative observation has to precede quantitative measurement, and by making experimental arrangements for quantitative measurements we may even eliminate the possibility of new phenomena appearing." Hendrik Casimir, born 15 July 1922.
"... some general method, capable of being employed in every case, is still wanting." George Green, born 14 July 1793.
"Our words are built on the objects of our experience. They have acquired their effectiveness by adapting themselves to the occurrences of our everyday world. But when we approach realities of another scale, these words can become obstacles." Hubert Reeves, born 13 July 1932.
"In fact, there really is not a new law of nature. It was all in the theory to begin with but nobody worked it out." Willis Lamb, born 12 July 1913.