The world of ideas is not revealed to us in one stroke; we must both permanently and unceasingly recreate it in our consciousness.

If one must choose between rigour and meaning, I shall unhesitatingly choose the latter.

All models divide naturally...into two a priori parts: one is kinematics, whose aim is to parameterize the forms of the states of the process under consideration, and the other is dynamics, describing the evolution in time of these forms.

The world of ideas is not revealed to us in one stroke; we must both permanently and unceasingly recreate it in our consciousness.

At a time when so many scholars in the world are calculating, is it not desirable that some, who can, dream ?

Topology is precisely the mathematical discipline that allows the passage from local to global.

Quantum mechanics, with its leap into statistics, has been a mere palliative for our ignorance