"I believe in the practice and philosophy of what we have agreed to call magic, in what I must call the evocation of spirits, though I do not know what they are, in the power of creating magical illusions, in the visions of truth in the depths of the mind when the eyes are closed; and I believe . . . that the borders of our mind are ever shifting, and that many minds can flow into one another, as it were, and create or reveal a single mind, a single energy . . . and that our memories are part of one great memory, the memory of Nature itself." 
​—W.B. Yeats, Ideas of Good and Evil