Let’s take a concrete example focused on a physical object first of all. In the perception of bodily present objects, their colour, shape, surface, length, width, brightness and clarity co-exist to form the perceptual whole (III, 95–96, IV, 177). In eidetic imaginative variation , it is possible to imagine a perceptual scene and vary the colour of a tea cup, say, and find that colour always co-occurs with the recognisable noematic sense of the tea cup shape. Furthermore, it is possible to vary the size of the tea cup shape or to switch to a different noetic form, say memory , and make further variations of both the noematic side or the noetic means of apprehending the noematic senses that comprise the object, tea cup. So, in this case variations in the visual field contain colour, shape and variations on the noematic profiles that comprise tea cup in general. In Husserl’s reasoning, an a priori law can be discerned that, for visual objects, colour, shape and size co-occur in order to constitute perceptual objects. In this example, the noesis-noema correlates are visual perceptions of a series of the object tea cup appearing across a number of noemata . The point for grounding the most fundamental intentional analysis is that through entirely experiential means, based on experience itself, it is possible to identify universal necessary essences about mental processes, personal and shared, and the meaning of the being of objects in their conditions of possibility for whole sets of noesis-noema correlations. In Husserl’s view such conclusions are not empirical but eidetic: meaning that they are not bound to individual phenomenologists or to any culturally-bound context and that they are theoretical conclusions that are derived from continua of whole ranges of instances.

The following remarks further explain: “Certain universalities as experienced are found also in the sphere of mere experience… in the skimming through, an overlapping of the perceptual givens takes place passively, and each given becomes an object of consciousness passively as a single moment of what is one common thing for sensuous passivity . But only a synthetic activity of comparing, of bringing to congruence, of distinguishing between what is identically common and what is different, yields synthetically constituted universalities and logical universal concepts. Then we have… universal terms, expressing logical universalities”, (IX, 98–99): which has the sense that patterns will appear across the manifold. Idealisation is used to spot what happens within an infinite series of possibilities of noesis-noema correlations. It is unnecessary to run through every member of an infinite series though. The work of running through variations refers to an infinite manifold: “an openly endless multiplicity of variants, in short, a variation. Of course this open infinity does not signify an actual continuation in infinity, the nonsensical demand actually to produce all possible variants—as if we could only then be sure that the eidos which subsequently becomes grasped actually accords with all possibilities”, (IX, 76–77): which implies that all forms of data can be made into a series of variants. The way of spotting universals and necessities is to run through the possibilities which are the ground of eidetic necessity, by carefully selecting examples beforehand, in order to spot patterns within a series of instances.

The eidetic sight of compossibility and incompossibility is another way of considering coherence about forms of meaning that differentiate between the noetic and noematic forms: “Separations are to be carried out on concrete lived-processes through analysis; there are components to be picked out according to sort, basic sorts, of non-selfsufficient moments to be distinguished; and every rational goal of a systematic analysis of lived-process is to be strived for with an immediately forthcoming multitude of special and completely determinate and obviously solvable problems”, (V, 41). This process of differentiation is the work that eidetics does for academia in specifying precisely what are the differences between talking, loving, planning, believing , problem-solving and so forth (VI, 252, XXV, 74).

Constancy of essences is assumed in being able to find a single eidos , a “multisignificant expression, a priori , that I recognize philosophically”, (XVII, 219). Although Husserl could have added that what he was looking at were always morphological structures on the object-side and noetic forms seen by looking across the ways in which noemata present themselves, comparatively across different givennesses. Such attention to essences creates a theory that “traces the infinity of deductive cognitions back to, or deduces them from, a small number of immediately evident truisms, its “Axioms”… but by no means is the entire science of the type of a mathematics”, (IX, 50). Another parallel between eidetics and the mathematical style of reasoning is highly apparent in “induction” in the mathematical sense of being able to recognise a progression across a series of numbers similarly to the movement across the original temporal field between protention, the now and retention that permits drawing conclusions on the character of the original temporal field (X, 119). What Husserl concluded as the irreal is the best characterisations of his view of conceptual intentionality with respect to its objects (EU, Sec. 64d). There are differing levels of eidetic research that generate findings concerning the universals and constants of how consciousness works in a general way. These noetic universals concern identifying forms of “the eidos , the essence “perception” and with what belongs to a “perception as such” as it were to the sense, ever the same, of possible perception in general”, (V, 40). This is what it means to conclude within intentional analysis about intentionality shared between persons in the world. During the years 1927–1929, facts get reinterpreted as essences and serve “only as an example and as the foundation for a free but intuitive variation of the factual mind and communities of minds into the a priori possible (thinkable) ones… There emerges therewith the eidetically necessary typical form, the eidos”, (IX, 284, cf I, 106, 140, 147, IX, 291, 323–324, 334). Eidetics includes the idea that regular patterns and processes arise and these can be expressed ideally without compromising the manifold.