From The Life of Samuel Johnson:

“The late ingenious Mr. Mickle, some time before his death, wrote me a letter concerning Dr. Johnson, in which he mentions: ‘I was upwards of twelve years acquainted with him, was frequently in his company, always talked with ease to him, and can truly say, that I never received from him one rough word.’ In this letter he relates his having while engaged in translating the Lusiad had a dispute of considerable length with Johnson, who, as usual, declaimed upon the misery and corruption of a sea life, and used this expression: ‘It had been happy for the world, Sir, if your hero Gama, Prince Henry of Portugal, and Columbus, had never been born, or that their schemes had never gone farther than their own imaginations.’

“‘This sentiment,’ says Mr. Mickle, ‘which is to be found in his Introduction to the World Displayed, I, in my Dissertation prefixed to the Lusiad, have controverted; and though authors are said to be bad judges of their own works, l am not ashamed to own to a friend, that that dissertation is my favourite above all that I ever attempted in prose. Next year, when the Lusiad was published, I waited on Dr. Johnson, who addressed me with one of his good-humoured smiles: ‘Well, you have remembered our dispute about Prince Henry, and have cited me too. You have done your part very well indeed: you have made the best of your argument; but I am not convinced yet.’

“‘Before publishing the Lusiad, I sent Mr. Hoole a proof of that part of the introduction in which I make mention of Dr. Johnson, yourself, and other well-wishers to the work, begging it might be shown to Dr. Johnson. This was accordingly done; and in place of the simple mention of him which I had made, he dictated to Mr. Hoole the sentence as it now stands.

“‘Dr. Johnson told me in 1772 that, about twenty years before that time, he himself had a design to translate the Lusiad, of the merit of which he spoke highly, but had been prevented by a number of other engagements.'”