From The Most Important Thing:
In investing, as in life, there are very few sure things. Values can evaporate, estimates can be wrong, circumstances can change and “sure things” can fail. However, there are two concepts we can hold to with confidence:
• Rule number one: most things will prove to be cyclical.• Rule number two: some of the greatest opportunities for gain and loss come when other people forget rule number one.
Very few things move in a straight line. There’s progress and then there’s deterioration. Things go well for a while and then poorly. Progress may be swift and then slow down. Deterioration may creep up gradually and then turn climactic. But the underlying principle is that things will wax and wane, grow and decline. The same is true for economies, markets and companies: they rise and fall.
The basic reason for the cyclicality in our world is the involvement of humans. Mechanical things can go in a straight line. Time moves ahead continuously. So can a machine when it’s adequately powered. But processes in fields like history and economics involve people, and when people are involved, the results are variable and cyclical. The main reason for this, I think, is that people are emotional and inconsistent, not steady and clinical.