[A] man ought to be prepared in a manner for this also, to be able to be sufficient for himself and to be his own companion. [...] [S]o ought we also to be able to talk with ourselves, not to feel the want of others also, not to be unprovided with the means of passing our time; to observe the divine administration and the relation of ourselves to everything else; to consider how we formerly were affected toward things that happen and how at present; what are still the things which give us pain; how these also can be cured and how removed; if any things require improvement, to improve them according to reason.