* I always work on problems which have already been tried by many, so it is (very) difficult and mistakes are inevitable.

* You can not invent anything in your lab which is not already there in nature. So, be humble. Stop being arrogant.

* Hilbert, das ist nicht Mathematik, das ist Theologie!

* Throw as much mud as you want, won't be rolling in it with you!

* Do not overload your boat.