'Science in itself' is nothing, for it exists only in the human beings who are its bearers. 'Science for its own sake' usually means nothing more than science for the sake of the people who happen to be pursuing it.

As long as vitalism and spiritualism are open questions so long will the gateway of science be open to mysticism.

Belief begins where science leaves off and ends where science begins.

Belief cannot be reckoned with in terms of science, for science and faith are mutually exclusive.

Belief has no place as far as science reaches, and may be first permitted to take root where science stops.

Brevity in writing is the best insurance for its perusal.

Disease is not something personal and special, but only a manifestation of life under modified conditions, operating according to the same laws as apply to the living body at all times, from the first moment until death.

If popular medicine gave the people wisdom as well as knowledge, it would be the best protection for scientific and well-trained physicians.

If the man of science chose to follow the example of historians and pulpit-orators, and to obscure strange and peculiar phenomena by employing a hollow pomp of big and sounding words, this would be his opportunity; for we have approached one of the greatest mysteries which surround the problem of animated nature and distinguish it above all other problems of science. To discover the relations of man and woman to the egg-cell would be almost equivalent of the egg-cell in the body of the mother, the transfer to it by means of the seed, of the physical and mental characteristics of the father, affect all the questions which the human mind has ever raised in regard to existence.

If we would serve science, we must extend her limits, not only as far as our own knowledge is concerned, but in the estimation of others.

Imprisoned quacks are always replaced by new ones.

Laws should be made, not against quacks but against superstition.

Life itself is but the expression of a sum of phenomena, each of which follows the ordinary physical and chemical laws. (1845)

Marriages are not normally made to avoid having children.

Medicine is a social science, and politics is nothing else but medicine on a large scale. Medicine, as a social science, as the science of human beings, has the obligation to point out problems and to attempt their theoretical solution: the politician, the practical anthropologist, must find the means for their actual solution.

No doubt science cannot admit of compromises, and can only bring out the complete truth. Hence there must be controversy, and the strife may be, and sometimes must be, sharp. But must it even then be personal? Does it help science to attack the man as well as the statement? On the contrary, has not science the noble privilege of carrying on its controversies without personal quarrels?

Only those who regard healing as the ultimate goal of their efforts can, therefore, be designated as physicians.

The personal views of the lecturer may seem to be brought forward with undue exclusiveness, but, as it is his business to give a clear exposition of the actual state of the science which he treats, he is obliged to define with precision the principles, the correctness of which he has proved by his own experience.

The physicians are the natural attorneys of the poor, and social problems fall to a large extent within their juristiction.

The task of science is to stake out the limits of the knowable, and to center consciousness within them.

The task of science, therefore, is not to attack the objects of faith, but to establish the limits beyond which knowledge cannot go and found a unified self-consciousness within these limits.

There can be no scientific dispute with respect to faith, for science and faith exclude one another.