A powerful agent is the right word. Whenever we come upon one of those intensely right words in a book or newspaper the resulting effect is physical as well as spiritual, and electrically prompt.
The earth doesn't belong to anyone. It is the land upon which all of us are to live for many years, ploughing, reaping and destroying. You are always a guest on this earth and have the austerity of a guest. Austerity is far deeper than owning only a few things. The very word austerity has been spoilt by the monks, by the sannyasis, by the hermits. Sitting on that high hill alone in the solitude of many things, many rocks and little animals and ants, that word has no meaning.
Inner peace is the key: if you have inner peace, the external problems do not affect your deep sense of peace and tranquility... Without this inner peace, no matter how comfortable your life is materially, you may still be worried, disturbed or unhappy because of circumstances.
Even today many educated people think that the victory of Christianity over Greek philosophy is a proof of the superior truth of the former - although in this case it was only the coarser and more violent that conquered the more spiritual and delicate. So far as superior truth is concerned, it is enough to observe that the awakening sciences have allied themselves point by point with the philosophy of Epicurus, but point by point rejected Christianity.