Leibniz wrote to Bourguet in defense of Leeuwenhoek, "to whom the public owes thanks".

Date: 
April 3, 1716

Leibniz replied to Bourguet's objections to Leeuwenhoek's ideas about the role of sperm by offering five points of refutation.

He ended with a sixth. "6th in all, let's not treat a man like Mr. Leeuwenhoek badly, to whom the public owes thanks for the pains he took in his research. It is very permissible to oppose his sentiment, and I am glad that one does so, but it is not right to despise him."

Document: 

Gothofredi Guillelmi Leibnitii, ... Opera omnia, nunc primum collecta, in classes distributa, praefationibus & indicibus exornata, studio Ludovici Dutens. Tomus primus sextus Tomus secundus, in duas partes distributus, quarum 1. continet logicam & metaphysicam; 2. physicam generalem, chymiam, medicinam, botanicam, historiam natu

Six Letters from Mr. Leibniz to Mr. Bourguet, p. 330