[In geology,] As in history, the material in hand remains silent if no questions are asked. The nature of these questions depends on the “school” to which the geologist belongs and on the objectivity of his investigations. Hans Cloos called this way of interrogation “the dialogue with the earth,” “das Gesprach mit der Erde.”

[The] subjective [historical] element in geologic studies accounts for two characteristic types that can be distinguished among geologists: one considering geology as a creative art, the other regarding geology as an exact science.

An example of such emergent phenomena is the origin of life from non-living chemical compounds in the oldest, lifeless oceans of the earth. Here, aided by the radiation energy received from the sun, countless chemical materials were synthesized and accumulated in such a way that they constituted, as it were, a primeval “soup.” In this primeval soup, by infinite variations of lifeless growth and decay of substances during some billions of years, the way of life was ultimately reached, with its metabolism characterized by selective assimilation and dissimilation as end stations of a sluiced and canalized flow of free chemical energy.

As geology is essentially a historical science, the working method of the geologist resembles that of the historian. This makes the personality of the geologist of essential importance in the way he analyzes the past.

Experiments in geology are far more difficult than in physics and chemistry because of the greater size of the objects, commonly outside our laboratories, up to the earth itself, and also because of the fact that the geologic time scale exceeds the human time scale by a million and more times. This difference in time allows only direct observations of the actual geologic processes, the mind having to imagine what could possibly have happened in the past.

Geology differs from physics, chemistry, and biology in that the possibilities for experiment are limited.

Geology is part of that remarkable dynamic process of the human mind which is generally called science and to which man is driven by an inquisitive urge. By noticing relationships in the results of his observations, he attempts to order and to explain the infinite variety of phenomena that at first sight may appear to be chaotic. In the history of civilization this type of progressive scientist has been characterized by Prometheus stealing the heavenly fire, by Adam eating from the tree of knowledge, by the Faustian ache for wisdom.

Half a century ago Oswald (1910) distinguished classicists and romanticists among the scientific investigators: the former being inclined to design schemes and to use consistently the deductions from working hypotheses; the latter being more fit for intuitive discoveries of functional relations between phenomena and therefore more able to open up new fields of study. Examples of both character types are Werner and Hutton. Werner was a real classicist. At the end of the eighteenth century he postulated the theory of “neptunism,” according to which all rocks including granites, were deposited in primeval seas. It was an artificial scheme, but, as a classification system, it worked quite satisfactorily at the time. Hutton, his contemporary and opponent, was more a romanticist. His concept of “plutonism” supposed continually recurrent circuits of matter, which like gigantic paddle wheels raise material from various depths of the earth and carry it off again. This is a very flexible system which opens the mind to accept the possible occurrence in the course of time of a great variety of interrelated plutonic and tectonic processes.

The functional validity of a working hypothesis is not a priori certain, because often it is initially based on intuition. However, logical deductions from such a hypothesis provide expectations (so-called prognoses) as to the circumstances under which certain phenomena will appear in nature. Such a postulate or working hypothesis can then be substantiated by additional observations ... The author calls such expectations and additional observations the prognosis-diagnosis method of research. Prognosis in science may be termed the prediction of the future finding of corroborative evidence of certain features or phenomena (diagnostic facts). This method of scientific research builds up and extends the relations between the subject and the object by means of a circuit of inductions and deductions.

The geologist applies a certain number of general views and concepts which are the rules for his scientific practice. Such premises, however, are less fixed than the natural laws postulated by the basic sciences of physics and chemistry. The geologist is therefore forced to test the validity of the greatest possible number of presuppositions (method of multiple working hypotheses).

There is, however, no universal recipe for scientific advance. It is a matter of groping forward into terra incognita of the outer world by means of methods which should be adapted to the circumstances.

We will be able to depart this life with the quiet peace-giving notion, that we were permitted to contribute to the happiness of many who will live after us. In our long lives we endeavored to unfold the collective consciousness. In our lives we have known hell and heaven; the final balance, however, is that we helped pave the way to dynamic harmony in this earthly house. That, I believe, is the meaning of this life.