Isaac Newton Quotes
Hypotheses should be subservient only in explaining the properties of things but not assumed in determining them, unless so far as they may furnish experiments.
Newton, Isaac. Letter to Henry Oldenburg, 8 July 1672. The Correspondence of Isaac Newton, edited by H.W. Turnbull, vol. 1, Cambridge UP, 1959, p. 206.
He was addressing the misunderstanding that many laypeople and most anti-evolutionists have that if Evolution is only a theory why put so much stock in it. The layman often uses the word “theory” in opposition to “fact.” But to the scientist theories are of different types—those that are as of yet speculation and those for which a strong body of evidence exists. Evolution, like Relativity, has a huge amount of evidence supporting it. Yet in time every good scientist knows that all these proven theories will be modified with new knowledge. Relativity has been demonstrated as having errors initially by Einstein himself. The essence of these things are true although elements change. The early law of gravity is the best example. We know that it is wrong in many, circumstances—in space for example. But it, none the less, is fundamental to much analysis and with our much more sophisticated understanding of it we still talk of the “Law” of gravity even though we realize that it is not quite correct in all circumstances.
This quotation illustrates and important aspect of science. Specifically, that theory, something ephemeral and impractical to the layman, has immense practical power in developing great scientific and technological breakthroughs. The result of this breakthrough was large lenses that could make lights more powerful and make lighthouses much more safe. Even the atomic bomb was really developed from theory and then engineered for practical use.
Sir Isaac Newton PRS was an English mathematician, physicist, astronomer, theologian, and author (described in his time as a "natural philosopher") who is widely recognised as one of the greatest mathematicians and most influential scientists of all time and as a key figure in the scientific revolution. His book Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), first published in 1687, established classical mechanics. Newton also made seminal contributions to optics, and shares credit with Gottfried Wilhelm Leibniz for developing the infinitesimal calculus.