"the Custom of our Learned in Europe to steal Inventions"
About fifty years before Gulliver's Travels was published, Isaac Newton and Gottfried Leibniz both worked out the principles of the calculus independently at about the same time. Questions arose about who was first and who deserved to get the credit. The controversy degenerated into vicious infighting and accusations of plagiarism filled the air. Swift alluded to that tumultuous controversy in this passage.