[The Book of Genesis is] [p]rofoundly interesting and indeed pathetic to me are those attempts of the opening mind of man to appease its hunger for a Cause. But the Book of Genesis has no voice in scientific questions. It is a poem, not a scientific treatise. In the former aspect it is for ever beautiful; in the latter it has been, and it will continue to be, purely obstructive and hurtful.'

From common salt are obtained chemically as primary derivatives chlorine—both a war gas and a means of purifying water; and 'caustic soda.' … [O]n the chlorine side there is obtained chloride of lime, (a bleaching powder and a disinfectant), chloroform (an anesthetic), phosgene (a frightful ware gas), chloroacetophenone (another war gas), and an indigo and a yellow dye. [O]n the soda side we get metallic sodium, from which are derived sodium cyanide (a disinfectant), two medicines with [long] names, another war gas, and a beautiful violet dye. Thus, from a healthful, preservative condiment come things useful and hurtful—according to the intent or purpose.

I look upon a good physician, not so properly as a servant to nature, as one, that is a counsellor and friendly assistant, who, in his patient’s body, furthers those motions and other things, that he judges conducive to the welfare and recovery of it; but as to those, that he perceives likely to be hurtful, either by increasing the disease, or otherwise endangering the patient, he thinks it is his part to oppose or hinder, though nature do manifestly enough seem to endeavour the exercising or carrying on those hurtful motions.

One of the largest promises of science is, that the sum of human happiness will be increased, ignorance destroyed, and, with ignorance, prejudice and superstition, and that great truth taught to all, that this world and all it contains were meant for our use and service; and that where nature by her own laws has defined the limits of original unfitness, science may by extract so modify those limits as to render wholesome that which by natural wildness was hurtful, and nutritious that which by natural poverty was unnourishing. We do not yet know half that chemistry may do by way of increasing our food.

The process of natural selection has been summed up in the phrase “survival of the fittest.” This, however, tells only part of the story. “Survival of the existing” in many cases covers more of the truth. For in hosts of cases the survival of characters rests not on any special usefulness or fitness, but on the fact that individuals possessing these characters have inhabited or invaded a certain area. The principle of utility explains survivals among competing structures. It rarely accounts for qualities associated with geographic distribution.
The nature of animals which first colonize a district must determine what the future fauna will be. From their specific characters, which are neither useful nor harmful, will be derived for the most part the specific characters of their successors.
It is not essential to the meadow lark that he should have a black blotch on the breast or the outer tail-feather white. Yet all meadow larks have these characters just as all shore larks have the tiny plume behind the ear. Those characters of the parent stock, which may be harmful in the new relations, will be eliminated by natural selection. Those especially helpful will be intensified and modified, but the great body of characters, the marks by which we know the species, will be neither helpful nor hurtful. These will be meaningless streaks and spots, variations in size of parts, peculiar relations of scales or hair or feathers, little matters which can neither help nor hurt, but which have all the persistence heredity can give.

To a new truth there is nothing more hurtful than an old error.

Water from clay pipes is much more wholesome than that which is conducted through lead pipes, because lead is found to be harmful for the reason that white lead is derived from it, and this is said to be hurtful to the human system.

When an hypothesis has come to birth in the mind, or gained footing there, it leads a life so far comparable with the life of an organism, as that it assimilates matter from the outside world only when it is like in kind with it and beneficial; and when contrarily, such matter is not like in kind but hurtful, the hypothesis, equally with the organism, throws it off, or, if forced to take it, gets rid of it again entirely.