"Keaton had been on the stage longest, risen the highest, fallen the furthest, and, thanks to the medium of film which preserved his artistry, left the most indelible legacy. ‘He was,’ Orson Welles said, ‘as we’re now beginning to realise, the greatest of all the clowns in the history of the cinema.’"
John Lahr @lrb
https://www.lrb.co.uk/the-paper/v45/n02/john-lahr/puzzled-puss