Finally his treatment of the problems of knowledge and of the foundations of science leads him to reemphasise not only the reality of spirit but its spontaneity. He recognises with Cournot and Renouvier that the vital problem for science and philosophy is that of freedom. The nature of existence is for Lachelier a manifestation of spirit, and is seen in will, in necessity and in freedom. It is important to note that for him it is _all_ these simultaneously. “Being,” he remarks in concluding his brilliant essay,[32] “is not first, a blind necessity, then a will which must be for ever bound down in advance to necessity and, lastly, a freedom which would merely be able to recognise such necessity and such a bound will; being is entirely free, in so far as it is self-creative; it is entirely an expression of will, in so far as it creates itself in the form of something concrete and real; it is also entirely an expression of necessity, in so far as its self-creation is intelligible and gives an account of itself.” [32] _Ibid_., p. 170. At this stage something in the nature of a temporary “set-back” is given to the flow of the spiritualist current by Fouillee’s attitude, which takes a different line from that of Ravaisson and Lachelier. The attitude towards Science, which we find adopted by Fouillee, is determined by his two general principles, that of reconcilation, and his own doctrine of _idées-forces_. His conciliatory spirit is well seen in the fact that, although he has a great respect for science and inherits many of the qualities contained in Taine’s philosophy, particularly the effort to maintain a regular continuity and solidarity in the development of reality, nevertheless he is imbued with the spirit of idealism which characterises all this group of thinkers. The result is a mixture of Platonism and naturalism, and to this he himself confesses in his work, _Le Mouvement idéaliste et la Réaction contre la Science positive_, where he expresses a desire “to bring back Plato’s ideas from heaven to earth, and so to make idealism consonant with naturalism.”[33] [33] _Le Mouvement idéaliste el la Réaction contre la Science positive_, p. xxi.