33. The regeneration of humanity does not absolutely require the complete renewal of the spirits. A modification in their moral dispositions suffices. This modification takes place with all those who are predisposed to it when they shall have freed themselves from the pernicious influence of the world. Those who return, then, are not always other spirits, but often the same ones, thinking and feeling otherwise.
When this amelioration is isolated and individual, it passes unperceived, and is without ostensible influences upon the world. Entirely different is the effect when it operates simultaneously over great masses of people; for then, according to the proportions of it in one generation, the ideas of a nation or a race can be profoundly modified by it.
This is observed after great accidents which decimate a population. The destructive scourges do not destroy the spirit, but only the body; they accelerate the coming-and-going movement between the corporeal and spiritual world, and consequently the progressive movement of incarnate and discarnate spirits. It has been observed, at all historical epochs that great social crises have been followed by an era of progress.