78     Some of these causes that exercise a modifying influence on the transformation of psora into chronic diseases manifestly depend sometimes on the climate and the peculiar physical character of the place of abode, sometimes on the very great varieties in the physical and mental training of youth, both of which may have been neglected, delayed or carried to excess, or on their abuse in the business or conditions of life, in the matter of diet and regimen, passions, manners, habits and customs of various kinds.