If the possibility of the spiritual development of all individuals is to be secured, a second kind of outward freedom is necessary. The development of science and of the creative activities of the spirit in general requires still another kind of freedom, which may be characterised as inward freedom. It is this freedom of the spirit which consists in the interdependence of thought from the restrictions of authoritarian and social prejudices as well as from unphilosophical routinizing and habit in general. This inward freedom is an infrequent gift of nature and a worthy object for the individual.

— Albert Einstein