Better to have no ideas than false ones

[This is a letter I wrote to James Madison, President of William and Mary, on July 19, 1788:]

As you seem willing to accept of the crumbs of science on which we are subsisting here, it is with pleasure I continue to hand them on to you, in proportion as they are dealt out. Herschel's volcano in the moon you have doubtless heard of, and placed among the other vagaries of a head, which seems not organized for sound induction. The wildness of the theories hitherto proposed by him, on his own discoveries, seems to authorize us to consider his merit as that of a good optician only.

You know also, that Dr. Ingenhouse had discovered, as he supposed, from experiment, that vegetation might be promoted by occasioning streams of the electrical fluid to pass through a plant, and that other physicians had received and confirmed this theory. He now, however, retracts it, and finds by more decisive experiments, that the electrical fluid can neither forward nor retard vegetation. Uncorrected still of the rage of drawing general conclusions from partial and equivocal observations, he hazards the opinion that light promotes vegetation. I have heretofore supposed from observation, that light effects the color of living bodies, whether vegetable or animal; but that either the one or the other receives nutriment from that fluid, must be permitted to be doubted of, till better confirmed by observation. It is always better to have no ideas, than false ones; to believe nothing, than to believe what is wrong. In my mind, theories are more easily demolished than rebuilt.