In his Prolegomena to Pure Logic Husserl works with Bolzano's idea that the entire field of truths can be partitioned into several parts, each of which consists of all truths "of a certain kind," that is, all truths that are germane to a certain homogeneous kind (Gattung) of objects.¹ Husserl says that "it is not arbitrary where and how we delimit fields of truth,"² "the domain of truth is not an unordered chaos,"³ but it is articulated in "natural provinces"⁴ that are also called "fields of knowledge (Erkenntnisgebiete)"⁵ or fields of experience (in a broad sense of this word which comports well with common mathematical usage, where, for instance, a system of abstract objects like e.g. the natural numbers equipped with certain functions and relations is said to be a "field of experience"). Each field of experience in Husserl's sense can be viewed as "an independent reality with its own experimentally determined mathematical structure."⁶ In this sense fields of "the purely mathematical sciences whose objects are numbers, manifolds (Mannigfaltigkeiten), etc., things thought of as mere bearers of ideal properties, independently from real being or not being,"⁷ are also to be considered fields of knowledge or of experience.⁸