Standing on the shoulders of giants
Using the understanding gained by major thinkers who have gone before in order to make intellectual progress.
The best-known use of this phrase was by Isaac Newton in a letter to his rival Robert Hooke, in 1676:
"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."
Newton didn't originate it though. The 12th century theologian and author John of Salisbury used a version of the phrase in a treatise on logic called Metalogicon, written in Latin in 1159. Translations of this difficult book are quite variable but the gist of what Salisbury said is:
"We are like dwarfs sitting on the shoulders of giants. We see more, and things that are more distant, than they did, not because our sight is superior or because we are taller than they, but because they raise us up, and by their great stature add to ours."
The phrase may even pre-date John of Salisbury, who was known to have adapted and refined the work of others.