But condition of health, sleep, nourishment, temperature, weather, surroundings, and much else that is purely external, have, in general, an important influence upon our mood and therefore upon our thoughts. Hence both our view of any matter and our capacity for any work are very much subject to time and place. So it is best to profit by a good mood--for how seldom it comes!--
_Nehmt die gute Stimmung wahr, Denn sie kommt so selten_.[1]
We are not always able to form new ideas about; our surroundings, or to command original thoughts: they come if they will, and when they will. And so, too, we cannot always succeed in completely considering some personal matter at the precise time at which we have determined beforehand to consider it, and just when we set ourselves to do so. For the peculiar train of thought which is favorable to it may suddenly become active without any special call being made upon it, and we may then follow it up with keen interest. In this way reflection, too, chooses its own time.
This reining-in of the imagination which I am recommending, will also forbid us to summon up the memory of the past misfortune, to paint a dark picture of the injustice or harm that has been done us, the losses we have sustained, the insults, slights and annoyances to which we have been exposed: for to do that is to rouse into fresh life all those hateful passions long laid asleep--the anger and resentment which disturb and pollute our nature. In an excellent parable, Proclus, the Neoplatonist, points out how in every town the mob dwells side by side with those who are rich and distinguished: so, too, in every man, be he never so noble and dignified, there is, in the depth of his nature, a mob of low and vulgar desires which constitute him an animal. It will not do to let this mob revolt or even so much as peep forth from its hiding-place; it is hideous of mien, and its rebel leaders are those flights of imagination which I have been describing. The smallest annoyance, whether it comes from our fellow-men or from the things around us, may swell up into a monster of dreadful aspect, putting us at our wits' end--and all because we go on brooding over our troubles and painting them in the most glaring colors and on the largest scale. It is much better to take a very calm and prosaic view of what is disagreeable; for that is the easiest way of bearing it.