Note 346 — Chapter III · The Opposition and Their Arguments.

One bit of contemporary opinion on Riccioli and his work has come down to us. A canon at Liège, Réné-François Sluse, wrote asking a friend (about 1670) to sound Wallis, the English mathematician, as to his opinion of the Almagestum Novum, and of this argument based on the acceleration of movement in falling bodies. Wallis himself replied that he thought the argument devoid of all value. The canon at once wrote, "I do not understand how a man as intelligent as Riccioli should think he could bring to a close a matter so difficult [the refutation] by a proof as futile as this." Monchamp: 165-166.

For a full, annotated list of books published against the Copernican system between 1631-1688, see Martin: Galilée: 386-388.