And these are the lines on which human nature ought to be trained, in school and out of school, from the day of birth to the day of death.

But they are lines on which it will never be trained so long as the doctrine of the depravity of Nature in general and human nature in particular controls our philosophy of life.
The doctrine of natural depravity, or original sin, is the outcome of Man's attempt to explain to himself the glaring fact of his own imperfection.

The doctrine grew up in an age when men were ignorant of the fundamental laws of Nature, and among a people who, though otherwise richly gifted, had no turn for sustained thought.

So long as men were ignorant of Nature's master law of evolution, it was but natural that they should account for their own imperfection by looking back to a Golden Age,--a state of innocence and bliss from which they had somehow fallen, and to which they could not, by any effort or process of their corrupted nature, hope to return.

While this idea--half myth and half doctrine--was growing up in the mind of Israel, the counter idea of the evolution or growth of the soul, of its ascent from "weak beginnings" towards a state of spiritual perfection, was growing up among the thinkers of India, and the derivative doctrine of salvation through the natural process of soul-growth was being gradually elaborated.