An event experienced is an event perceived, digested, and assimilated into the substance of our being, and the ratio between the number of cases seen and the number of cases assimilated is the measure of experience.

The dispassionate intellect, the open mind, the unprejudiced observer, exist in an exact sense only in a sort of intellectualist folk-lore states even approaching them cannot be reached without a moral and emotional effort most of us cannot or will not make.

It is necessary to guard ourselves from thinking that the practice of the scientific method enlarges the powers of the human mind. Nothing is more flatly contradicted by experience than the belief that a man distinguished in one or even more departments of science, is more likely to think sensibly about ordinary affairs than anyone else.

The mind likes a strange idea as little as the body likes a strange protein and resists it with similar energy. It would not perhaps be too fanciful to say that a new idea is the most quickly acting antigen known to science.

Disease often tells its secrets in a casual parenthesis.

If we watch ourselves honestly we shall often find that we have begun to argue against a new idea even before it has been completely stated.

The second thing to be striven for is intuition. This sounds an impossibility, for who can control that small quiet monitor? But intuition is only interference from experience stored and not actively recalled.

The fundamental activity of medical science is to determine the ultimate causation of disease.

The truly scientific mind is altogether unafraid of the new, and while having no mercy for ideas which have served their turn or shown their uselessness, it will not grudge to any unfamiliar conception its moment of full and friendly attention, hoping to expand rather than to minimize what small core of usefulness it may happen to contain.

It was not noisy prejudice that caused the work of Mendel to lie dead for thirty years, but the sheer inability of contemporary opinion to distinguish between a new idea and nonsense.