 For whatever reasons, Kant seems to have been unsatisfied by this initial attempt, and so set out in the 1760s to better defend and explain this same general system of thought in his Only Possible Argument in Support of a Demonstration of the Existence of God (1763b). This time, however, he is much more concerned with articulating a firm methodological basis for his metaphysics, as is evident in the work itself as well as in the key essays of the period, Attempt to Introduce the Concept of Negative Magnitudes into Philosophy (1763a) and Inquiry Concerning the Distinctness of the Principles of Natural Theology and Morality (1764).