Sentence:  The Neo Platonic philosophy, it will now be seen, is monism, and the completion, consequently, of ancient philosophy, so far as it would reduce the totality of being to a single ultimate ground. As able, however, to find its highest principle, from which all the rest are derived, not through self-consciousness and natural rational explanation, but only through ecstasy, mystic annihilation of self, <WSD>ascesis</WSD>, theurgy, it is a desperate overleaping of all—and, consequently, the self-destruction of ancient—philosophy. 
Meaning of the word marked with <WSD> tags:  (Rigorous) self-discipline, particularly as a religious observance; asceticism.