One of the common Buddhist similes for human life is fire and it is the best simile for illuminating all Buddhist psychology. To insist on finding a soul is like describing flames as substances. Fire is often spoken of as an element but it is really a process which cannot be isolated or interrupted. A flame is not the same as its fuel and it can be distinguished from other flames. But though you can individualize it and propagate it indefinitely, you cannot isolate it from its fuel and keep it by itself. Even so in the human being there is not any soul which can be isolated and go on living eternally but the analogy of the flame still holds good. Unseizable though a flame may be, and undefinable as substance, it is not unreasonable to trim a fire and make a flame rise above its fuel, free from smoke, clear and pure. If it were a conscious flame, such might be its own ideal. The eighth and last section of the path is sammâ-samâdhi, right concentration or rapture. Mental concentration is essential to samâdhi, which is the opposite of those wandering desires often blamed as seeking for pleasure here and there. But samâdhi is more than mere concentration or even meditation and may be rendered by rapture or ecstasy, though like so many technical Buddhist terms it does not correspond exactly to any European word. It takes in Buddhism the place occupied in other religions by prayer—prayer, that is, in the sense of ecstatic communion with the divine being. The sermon[485] which the Buddha preached to King Ajâtasattu on the fruits of the life of a recluse gives an eloquent account of the joys of samâdhi. He describes how a monk[486] seats himself in the shade of a tree or in some mountain glen and then "keeping his body erect and his intelligence alert and intent" purifies his mind from all lust, ill-temper, sloth, fretfulness and perplexity. When these are gone, he is like a man freed from jail or debt, gladness rises in his heart and he passes successively through four stages of meditation[487]. Then his whole mind and even his body is permeated with a feeling of purity and peace. He concentrates his thoughts and is able to apply them to such great matters as he may select. He may revel in the enjoyment of supernatural powers, for we cannot deny that the oldest documents which we possess credit the sage with miraculous gifts, though they attach little importance to them, or he may follow the train of thought which led the Buddha himself to enlightenment. He thinks of his previous births and remembers them as clearly as a man who has been a long walk remembers at the end of the day the villages through which he has passed. He thinks of the birth and deaths of other beings and sees them as plainly as a man on the top of a house sees the people moving in the streets below. He realizes the full significance of the four truths and he understands the origin and cessation of the three great evils, love of pleasure, love of existence and ignorance.