Jockey Club "Handicapper" W. S. Vosburgh on the subject with one of his typical brutally long winded columns from the late 1910's.
This was in a period of no speed figures - No Beyers, no Ragozin Sheets etc. Obviously - figures are king in discussions on subjects like these.
Later on - the subject of old jockeys naming the best they've ever seen...
It's cuts off talking about Hindoo and Luke Blackburn. Basically, both were in the same stable and ridden by the same jockey. When asked to name the better horse - the trainer favored Hindoo. While the jockeys reply was always "Luke Blackburn, of course"