Don't become a mere recorder of facts, but try to penetrate the mystery of their origin.
Ivan Pavlov

While you are experimenting, do not remain content with the surface of things.
Ivan Pavlov

But man has still another powerful resource: natural science with its strictly objective methods.
Ivan Pavlov

Perfect as the wing of a bird may be, it will never enable the bird to fly if unsupported by the air. Facts are the air of science. Without them a man of science can never rise.
Ivan Pavlov

It is clear to all that the animal organism is a highly complex system consisting of an almost infinite series of parts connected both with one another and, as a total complex, with the surrounding world, with which it is in a state of equilibrium.
Ivan Pavlov

It goes without saying that the desire to accomplish the task with more confidence, to avoid wasting time and labour, and to spare our experimental animals as much as possible, made us strictly observe all the precautions taken by surgeons in respect to their patients.
Ivan Pavlov

Finally, as the digestive canal is a complex system, a series of separate chemical laboratories, I cut the connections between them in order to investigate the course of phenomena in each particular laboratory; thus I resolved the digestive canal into several separate parts.
Ivan Pavlov