These remarks are parts of a historical research on the ideological functions of Catastrophism. It is suggested that in mediaeval monasticism the closing of time might have contributed to the unprecedented technical development of Western European culture between the Xth and the XVth centuries. The opening of time and space conveyed by the scientific and industrial revolutions have led to the ideologies of illimited progressand indefinite growth today officially prevailing in the whole world. It is questionned whether the closing of time inherent to the contemporary ecological movement, as illustrated by Economist Georgescu-Roegen, will contribute to the psycho-sociological mutation indispensable if mankind is to survive.