Condorcet was the last of the encyclopaedists : a "geometer" and fervent advocate of “public good”, he believed in the unlimited progress of the human mind and knowledge. Reason, which had served the natural sciences so well, had henceforth to serve the “moral sciences”, whose aim is human happiness. He was the first to propose and think out “social mathematics”. While the nineteenth century paid almost no heed to that, for half a century now he has gained academic renown as a forerunner of mathematics applied to the social sciences. The present article traces the evolution of his ideas – especially his early reluctance, which is shared by some people today. It ... looks at other less well-known aspects of his thought, such as the importance he attached to “the art of making tables” and the devising of an universal language which would enable every one to share scientific knowledge.