I am most grateful for your interesting letter concerning reality, particularly for the circumspection and consideration you show by informing me, a stranger, on just how your epoch goes about determining what is real and what is not. You stress what you call scientific analysis and objectivity. I can assure you that such demands were not peculiar to your age: I am indeed addressing myself to precisely such a mentality in my Essay on Zoological Method. There are those who would explain everything by natural forces; there are others who insist that the good Lord created it all. We are encroaching neither on the wisdom nor the power of the Creator to assume that he works indirectly, through nature, nor do we belittle pristine nature if we assume that she was indirectly involved at the beginning.
Is it not appropriate to the dignity of a primaeval force to accomplish what is simple simply, and what is complex, by complex means? Is it too much if I remark that fish cannot be created without water, birds without air, or the other animals without the earth--why, they cannot even be imagined apart from the conditions imposed upon them by these same elements? The more satisfying view upon the mysteries of natural development calls for interaction between the unique type and its environment. Both entities require detailed, yet holistic investigation.
Thus we shall proceed in this line of study. As we are just now learning to regard unorganized, indeterminate elements as the seedbed of anorganic compounds, we shall in future advance our observations to understand the organic world as also a combination of its own components. The entire plant kingdom, for example, will appear to us as another tremendous sea, quite as necessary for the conditioned existence of the insects as are oceans and rivers for the conditioned existence of the fish, and we shall see that a tremendous number of living creatures are born and nourished in this plant sea, indeed we shall finally regard the entire animal world only as one more great element where each species has its continuation in and from the other, if not its very origin. We shall accustom ourselves to regard relationships and connections as something other than predetermined or purposeful, and in this way alone shall we make progress in understanding how formative nature manifests herself, everywhere and in every direction. And our experience will convince us, as has the progress of science hitherto, that the most palpable and extensive utility for mankind requires great unselfish efforts which do not demand to be paid at the end of each week like some day-laborer, but need not even show their usefulness for humanity at the end of a decade, or a century.
In the hope, my dear professor, that you neither regard such a comprehensive view as "unrealistic" nor feel that I am straying from your subject as to just where "reality" might lie, I remain your faithful
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