Isaac Newton famously remarked in a letter to his rival Robert Hooke dated February 5, 1676 that:

"What Descartes did was a good step. You have added much several ways, and especially in taking the colours of thin plates into philosophical consideration. If I have seen a little further it is by standing on the shoulders of Giants."

This has recently been interpreted by a few writers as a sarcastic remark directed against Hooke. This is speculative; Hooke and Newton had exchanged many letters in tones of mutual regard, and Hooke was not of particularly short stature, although he was of slight build and had been afflicted from his youth with a severe stoop. However, at some point, when Robert Hooke criticized some of Newton's ideas regarding optics, Newton was so offended that he withdrew from public debate. The two men remained enemies until Hooke's death.