In order to complete our discussion science we need to consideration the actual practice of science. In part this is because Newton did so much to determine how scientists in succeeding generations would practice their profession collectively. The success of science in the years following Newton, however, lays not so much in Newton and his predecessors having laid down a single method of work for individual scientists, but rather in a peculiar adjustment that mediates between the public and private practice of science. Private science is that phase in the scientific enterprise of individual achievement, a single scientist or a research team working as one. Public science, on the other hand, is the entire body of science into which individual contributions are brought. Understanding the distinction between the practice of private and public science is crucial if one is to understand science.
It is during the period of individual effort that the processes of science are most difficult to characterize. In years past, when scientists felt less constrained in expressing their innermost thoughts, a nonrational, mystical, or even religious conviction was often freely acknowledged as motivating their work. For example to understand the achievements of such monuments in seventeenth century science as Descartes (1596-1650), Newton, and Leibniz (1646-1716), one must understand the importance of theology in their perspective of human existence. Progress in science has so often depended on an unflinching tenacity by its practitioners. But it is precisely because private science has been able to accommodate irrational elements that the drive to discover has not been extinguished even under the most adverse conditions. We cannot but conclude that intense scientific activity must provide a unique exhilaration and deep sense of fulfillment to have maintained the dedication shown by individual scientists. Henri Poincare'(1854-1912) said it best when he state that, "...intellectual beauty is sufficient unto itself, and it is for its sake, more perhaps than for the future good of humanity, that the scientist devotes himself to long and difficult labors."
How can such a degree of personal commitment by individual scientists not endanger the search for objective truth? Objectivity is, apparently, imposed during the transition from private to public science, assuming it does not already exist. For only when the private stage is over and the individual contribution is formalized for absorption into public science is it that each step and concept must be clear and meaningful to the scientific community if it is to be accepted. Also nonrational tenets of individual scientists are generally so varied, so vague, and so technically inept that they cannot survive simply by the lack of a basis for general acceptance and agreement. Consequently, nonrational elements are left standing in the wings when private science is ushered on to the public stage for its consideration. For what we have is a paradox in the methods of science. In the creative process, scientists may allow themselves to work and think in undecipherable ways, like creative artists, but later they must take on the role of the public scientist and speak in terms of facts, figures, and in a logical sequence of thought.
Science depends on the correct observation and classification of facts, and yet nothing can be more deceptive than facts. As noted by Aldous Huxley (1894-1963), "Facts are ventriloquists' dummies; sitting on a wise man's knee they may be made to utter words of wisdom; elsewhere, they say nothing, or talk nonsense, or indulge in sheer diabolism." Part of the problem with facts is that it is virtually impossible to discuss them without indulging in some unspoken interpretation or hypothesis. Facts cannot be discerned by themselves without intellectual tools for handling our sense impressions. Scientists do have preconceptions or "themes" and do use them in developing facts about phenomena.
This admission seems to contradict the popular notion that the first step in science is to abandon all prejudgments. However, we contend that without preconceptions one cannot conceive new thoughts. It is thought that gives scientists' eyes to perceive the world. And in short, the pattern we perceive when we note "a fact" is organized and interpreted by a whole system of thoughts, attitudes, memories, beliefs, and learned constructs. To understand even the simplest observations, each scientist places that observation in the context of a distilled wisdom of science as an institution. As so beautifully stated by Sir Michael Foster (1836-1907), "What we are is in part only of our making. The greater part of ourselves has come down to us from the past. What we know and what we think is not a new fountain gushing fresh from the barren rock of the unknown at the stroke of the rod of our own intellect: It is a stream which flows by us and through us, fed by the far off rivulets of long ago."