In thus explaining mental impressions, the Epicureans do not allow themselves to be disturbed by the fact that we can recall at pleasure the ideas of all possible things. The cause of this power was rather supposed to be the circumstance that we are always surrounded by an innumerable number of atom-pictures, none of which we perceive unless our attention is directed to them. Likewise the seeming motion of forms which we behold in dreams is explained by the hasty succession of similar atom-pictures, appearing to us as changes of one and the same picture. [1235] But besides receiving pictures supplied from without, spontaneous motion with regard to these pictures takes place on our part, a motion connected in the first instance with the soul’s motion when it receives the outward impression, but not to be regarded as a simple continuation thereof. This independent motion gives rise to opinion, and hence opinion is not so necessary or so universally true as feeling. It may agree with feeling, or it may not agree with it. It may be true or it may be false. [1236] The conditions of its being true or false have been previously investigated. [1237] [(4) Will.] Impressions also give rise to will and action, the soul being set in motion by impressions, and this motion extending from the soul to the body. [1238] Into the nature of will, however, Epicurus does not appear to have instituted a more careful psychological investigation. It was enough for him to assert the freedom of the will. This freedom he considers absolutely indispensable, if anything we do is to be considered our own, unless we are prepared to despair of moral responsibility altogether, and to resign ourselves to a comfortless and inexorable necessity. [1239] To make freedom possible, Epicurus had introduced accident into the motion of atoms, and for the same reason he denies the truth of disjunctive propositions which apply to the future. [1240] In the latter respect, he, no doubt, only attacked the material truth of two clauses, without impugning the formal accuracy of the disjunction, [1241] i.e. he did not deny that of two contradictory cases either one or the other must happen, nor did he deny the truth of saying: To-morrow Epicurus will either be alive or not alive. But he disputed the truth of each clause taken by itself. He denied the truth of the sentence, Epicurus will be alive; and equally that of its contradictory, Epicurus will not be alive; on the ground that the one or the other statement only becomes true by the actual realisation of an event at present uncertain. [1242] For this he deserves little blame. Our real charge against him is that he did not more thoroughly investigate the nature of the will and the conception of freedom, and that he treats the subject of the soul as scantily and superficially as he had treated the subject of nature. CHAPTER XVIII. VIEWS OF EPICURUS ON RELIGION. [A. Criticism of the gods and the popular faith.]