We must trust to nothing but facts: These are presented to us by Nature, and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.

Any chemist reading this book can see, in some detail, how I have spent most of my mature life. They can become familiar with the quality of my mind and imagination. They can make judgements about my research abilities. They can tell how well I have documented my claims of experimental results. Any scientist can redo my experiments to see if they still work—and this has happened! I know of no other field in which contributions to world culture are so clearly on exhibit, so cumulative, and so subject to verification.

Have you heard the joke about the chemist, physicist and economist who get wrecked on a desert isle, with a huge supply of canned baked beans as their only food? The chemist says that he can start a fire using the neighbouring palm trees, and calculate the temperature at which a can will explode. The physicist says that she can work out the trajectory of each of the baked beans, so that they can be collected and eaten. The economist says "Hang on guys, you're doing it the hard way. Let's assume we have a can opener.