The mode of conscious differentiation is the mode of immediate sense-experience: our experience of instantaneous change in an omnipresent experiential moment (the eternal "now."

The mode of conscious integration is the mode of cumulative change over time, or narrative (a more accurate term than "language." Our perception of stories of change over time (A duration.)

The Fundamental Theorem of Calculus states that integration and differentiation are inverse operations of the same process. When applied to these modes of perception it implies that these modes of perception are mutually necessary co-equals, neither representing a more fundamental view of reality. It is processually monistic but perceptually dualistic.

A suggested answer to the question "Why does calculus integration and differentiation correspond to modes of conscious perception?" is "Because the FToC is an expression of the metaphysical nature of change, and thus necessarily expressed in every domain from mathematics to perception."
Could calculus-based phenomenology be the key to the ancient and seemingly unachievable dream of making metaphysics a science?