In the practice of the two sciences, co-operation has often been achieved, even though its theoretical basis has been little explored. From the earliest beginnings of his craft the engineer has been concerned to provide substitutes for human function or to improve human capacities. The development of machines supplementing the labour of man's hands provides a classical example. It is perhaps less generally realized that the result of the development of mechanical substitutes for a function has been to revolutionize the approach by biologists to that function itself. With the invention of machines that do useful work went the refinement of the concept of energy and of the mathematical and other methods for dealing with the subject.
3. Only then was it possible for the biologist to find an objective language for describing the work done by a living body. Armed with the instruments and concepts of physicists, chemists and engineers, the biologist was able to make new discoveries about the energy requirements of the body and how they are met. Thus the creation of new tools and of the language, in which they are described, not only gives a man new power over nature but also over himself.
В тексте нет модальных глаголов, но есть их эквиваленты.