Paul Sabatier quotes:

During the period 1901 to 1905, together with Senderens, I showed that nickel is very suitable for the direct hydrogenation of nitriles into amines and, no less important, of aldehydes and acetones into corresponding alcohols.

Theories cannot claim to be indestructible. They are only the plough which the ploughman uses to draw his furrow and which he has every right to discard for another one, of improved design, after the harvest.

My own ideas on the mechanism of catalytic phenomena were very different from those at one time commonly held, ideas which I no doubt owed to the influence of the illustrious teacher who had guided my first steps in chemistry nearly twenty years before - I refer, of course, to Berthelot.