Every description of anything is a projection. Physics describes the world in space and time; mathematics in number; philosophy in existence and cause. Each of these is a medium, and none of them need belong to the thing described. So a simple question follows, and it turns out to have a precise answer: what is left when you refuse to pay with any of them?

Boris Kriger went looking for the floor of thought, the level beneath which no one can go without losing the ability to speak, and found that it has exactly four boards. You cannot deny difference without differing from your own denial. You cannot deny identity without holding the word "nothing" steady across the sentence. You cannot deny that anything follows from anything without offering the denial as something that follows. And you cannot deny choice without choosing to say so. Difference, Identity, Conditionality, Taking: DICT. There is no fifth. Three are not enough. And logic, arithmetic, geometry, and physics turn out not to be rival foundations but four different currencies in which the same small debt is paid.

This book tells the story of that search in the author's own voice, including the two places where he got it wrong and the reviewer who caught him. It then takes the resulting method for a walk: through the vacuum, which is not nothing for reasons that are pure grammar; through gravity, which asks only whether you are there; through entropy, money, death, black holes, the sentence about God that cannot be finished, and a jar of sour cream, included as a test of scale. Along the way it proposes a discipline for thinking about anything at all: descend first, see what remains, and then bring space, time, and number back on purpose, with a receipt.

A theory that assumes almost nothing has almost nowhere to be wrong. This one shows where.