We do not know many things. We seem to learn few things as time passes but there is this nagging feeling of incomprehensibility. Here is a quote from Oksendal's Stochastic Differential Equations:
We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things.
- Posted outside the mathematics reading room, Tromso University
_____________________________