The most commonplace things are in fact mysteries.
Whether gloomy weather causes gloomy people or the reverse, is one. You must have noticed the connection: Australia plays a dismal Ashes series and southern Australia is plunged into three months of cloudy, rainy nights.
What is causality anyway? Does a traffic jam cause me to be late, or do people being in a hurry to make up lost time cause traffic jams? Do we choose the people we are most likely to break up with, or do they choose us?
You could say quite validly that the daily inching of the constellations over the eastern horizon causes the year and the seasons, while knowing full well the contingency of your perspective. We know the cause of the phases of the Moon, but they only exist from our perspective, so don’t we cause them really?
Perhaps not only the tropical foundations of personality, but the seasons themselves, are of our own making.