Sir Isaac Newton explains the scientific method

In 1703, Isaac Newton (1642 - 1727) was elected President of the Royal Society. He retained the Presidency until his death. The Royal Society became the chief expression of scientific opinion in Europe under his leadership.

Newton declared that the purpose of the Royal Society was to deliberate on Natural Philosophy which consists of "discovering the frame and operations of Nature, and reducing them, as far as may be, to general Rules or Laws - establishing these Rules by observations and experiments, and thus deducing the cause and effects of things." This became the working definition of the scientific method.

In 1704 Newton presented his studies of optics to the Royal Society. He declared his intent "is not to explain the Properties of Light by Hypothesis, but to propose and prove them by Reason and Experiment". He set out his vision of experimental science as an alternative to the hypotheses and theoretical principles of the natural philosophers who had considered the phenomenum of Light, in the past.

Source: Brief Lives - Newton by Peter Ackroyd, Chapter 15.