Small-scale acts of helping are more common than large-scale acts of helping, because helping is gratifying, and the gratification scales less than linearly with amount of good done. Small-scale acts of helping can be explained by a purely egoistic model, and there are fewer large-scale acts of helping than can be explained by a purely altruistic model, but there are still more large-scale acts of helping than can be explained by a purely egoistic model.
Small-scale acts of helping are more common than large-scale acts of helping, because helping is gratifying, and the gratification scales less than linearly with amount of good done. Small-scale acts of helping can be explained by a purely egoistic model, and there are fewer large-scale acts of helping than can be explained by a purely altruistic model, but there are still more large-scale acts of helping than can be explained by a purely egoistic model.
Fair summary?
Pretty much.