“Men die of the diseases which they have studied most,” remarked the surgeon, snipping off the end of a cigar with all his professional neatness and finish. “It’s as if the morbid condition was an evil creature which, when it found itself closely hunted, flew at the throat of its pursuer. If you worry the microbes too much they may worry you. I’ve seen cases of it, and not necessarily in microbic diseases either. There was, of course, the well-known instance of Liston and the aneurism; and a dozen others that I could mention.”

A bewildering assortment of (mostly microscopic) life-forms has been found thriving in what were once thought to be uninhabitable regions of our planet. These hardy creatures have turned up in deep, hot underground rocks, around scalding volcanic vents at the bottom of the ocean, in the desiccated, super-cold Dry Valleys of Antarctica, in places of high acid, alkaline, and salt content, and below many meters of polar ice. ... Some deep-dwelling, heat-loving microbes, genetic studies suggest, are among the oldest species known, hinting that not only can life thrive indefinitely in what appear to us totally alien environments, it may actually originate in such places.

A single tree by itself is dependent upon all the adverse chances of shifting circumstances. The wind stunts it: the variations in temperature check its foliage: the rains denude its soil: its leaves are blown away and are lost for the purpose of fertilisation. You may obtain individual specimens of line trees either in exceptional circumstances, or where human cultivation had intervened. But in nature the normal way in which trees flourish is by their association in a forest. Each tree may lose something of its individual perfection of growth, but they mutually assist each other in preserving the conditions of survival. The soil is preserved and shaded; and the microbes necessary for its fertility are neither scorched, nor frozen, nor washed away. A forest is the triumph of the organisation of mutually dependent species.

I can think of a few microorganisms, possibly the tubercle bacillus, the syphilis spirochete, the malarial parasite, and a few others, that have a selective advantage in their ability to infect human beings, but there is nothing to be gained, in an evolutionary sense, by the capacity to cause illness or death. Pathogenicity may be something of a disadvantage for most microbes…

If it is a terrifying thought that life is at the mercy of the multiplication of these minute bodies [microbes], it is a consoling hope that Science will not always remain powerless before such enemies...

In the nineteenth century men lost their fear of God and acquired a fear of microbes.

It has been demonstrated that a species of penicillium produces in culture a very powerful antibacterial substance which affects different bacteria in different degrees. Generally speaking it may be said that the least sensitive bacteria are the Gram-negative bacilli, and the most susceptible are the pyogenic cocci ... In addition to its possible use in the treatment of bacterial infections penicillin is certainly useful... for its power of inhibiting unwanted microbes in bacterial cultures so that penicillin insensitive bacteria can readily be isolated.

It is usually not recognized that for every injurious or parasitic microbe there are dozens of beneficial ones. Without the latter, there would be no bread to eat nor wine to drink, no fertile soils and no potable waters, no clothing and no sanitation. One can visualize no form of higher life without the existence of the microbes. They are the universal scavengers. They keep in constant circulation the chemical elements which are so essential to the continuation of plant and animal life.

Microbiology is usually regarded as having no relevance to the feelings and aspirations of the man of flesh and bone. Yet, never in my professional life do I find myself far removed from the man of flesh and bone. It is not only because microbes are ubiquitous in our environment, and therefore must be studied for the sake of human welfare. More interesting, and far more important in the long run, is the fact that microbes exhibit profound resemblances to man. They resemble him in their physical makeup, in their properties, in their responses to various stimuli; they also display associations with other living things which have perplexing and illuminating analogies with human societies.

The active agent is readily filterable and the name “penicillin” has been given to filtrates of broth cultures of the mould. … It is suggested that it may be an efficient antiseptic for application to, or injection into, areas infected with penicillin-sensitive microbes.

The first telescope opened the heavens; the first microscope opened the world of the microbes; radioisotopic methodology, as examplified by RIA [radioimmunoassay], has shown the potential for opening new vistas in science and medicine

The greatest possibility of evil in self-medication [with penicillin] is the use of too-small doses, so that, instead of clearing up the infection, the microbes are educated to resist penicillin and a host of penicillin-fast organisms is bred out which can be passed on to other individuals and perhaps from there to others until they reach someone who gets a septicemia or a pneumonia which penicillin cannot save. In such a case the thoughtless person playing with penicillin treatment is morally responsible for the death of the man who finally succumbs to infection with the penicillin-resistant organism. I hope this evil can be averted.

Theories and schools, like microbes and globules, devour each other and by their struggle ensure the continuing of life.

Why then be concerned about the conservation of wildlife when for all practical purposes we would be much better off if humans and their domestic animals and pets were the only living creatures on the face of the earth? There is no obvious and demolishing answer to this rather doubtful logic although in practice the destruction of all wild animals would certainly bring devastating changes to our existence on this planet as we know it today… The trouble is that everything in nature is completely interdependent. Tinker with one part of it and the repercussions ripple out in all directions… Wildlife—and that includes everything from microbes to blue whales and from a fungus to a redwood tree—has been so much part of life on the earth that we are inclined to take its continued existence for granted… Yet the wildlife of the world is disappearing, not because of a malicious and deliberate policy of slaughter and extermination, but simply because of a general and widespread ignorance and neglect.