uniform. 2. One of the watches might be constantly regulated, so as to keep it uniform with the other. 3. The watchmaker might be so skillful as to be able to make both go together, though independent of one another. As between body and soul, the first contrivance is clearly impossible. The second, which agrees with the occasionalist doctrine, is unworthy of God, whom it employs as a Deus ex machina. The third then remains, and here we find again Leibnitz's peculiar doctrine of Preëstablished Harmony.
But these and all similar views are discredited by the more recent investigations of natural science, and are void of all influence in modern thought, by reason of the dualistic principle on which they rest, in conformity to their semi-theological origin. The propounders of these theories start out from the hypothesis of a spiritual substance absolutely diverse from the body, viz., the soul, and their study is to investigate its association with the body. They find that the coupling of these two substances is possible only by a miracle, and that even after this first miracle another association of the two cannot take place except by means of a fresh miracle, or of a continuous miracle, dating from creation. This consequence they give out as a new solution of the problem, though they never took sufficient pains to inquire whether they themselves have not attributed to the soul such a nature that mutual interaction between it and the body is unthinkable. In short, the most satisfactory demonstration of the impossibility of the interaction of soul and body leaves room to question whether the premises were not arbitrary, and whether consciousness may not be regarded as simply the effect of matter, and so perhaps understood. Hence, the student of natural science demands that the argument to show that mental phenomena are unintelligible from their material conditions shall have nothing to do with any hypothesis as to the origin of such phenomena.
Astronomical knowledge of a material system I call such a knowledge of all its parts, their respective positions and their motions, that their position and motion, at any given time, past or future, may be calculated with the same certainty as we calculate the position and motion of the heavenly bodies, by means of previous absolute accuracy of observation and perfection of theory. To get the differential equation whose integration will give the desired results, we need only have, as it were, three positions of the parts of the system; i. e., we must know the position of the parts of the system at three successive instants, separated by two differentials of time. From the difference of the courses run in the equal and infinitesimal periods of time between the three we deduce the forces acting upon the system and within it.
In our incapacity to comprehend matter and force, astronomical knowledge of a material system is the completest knowledge we can expect to acquire of it. With this our instinct of causality is wont to be satisfied, and this is the kind of knowledge that would be possessed