D'Alembert's 'Tree of Knowledge', 1751.
© Science Museum / Science & Society Picture Library
Plate from the 1963 translation by Richard Schwab of d'Alembert's 'Preliminary Discourse on the Encyclopaedia of Diderot', (c 1751). Jean le Rond d'Alembert (1717-1783) was a French mathematician and philosopher who made important contributions to mechanics. Until 1758 he was Denis Diderot's (1713-1784) principal collaborator on 'Le Grand Encyclopedie', published between 1751 and 1765. The 'Preliminary Discourse' proclaimed the philosophy of the French Enlightenment.