As the tune proceeds, note 8 recedes further into the past and 'appears' in ever-changing 'retentional modifications'. Thus I retain not only the individual notes of the tune, but the order in which they occurred. I 'protain' its future course. If I have not heard the tune before, my protention is less determinate than my retention, but following a tune involves an expectation that its future course will lie within certain limits. Ordinary, or 'secondary', memory presupposes, but is distinct from, retention, or 'primary' memory.
Expectation similarly presupposes, but is distinct from, protention.
The act of consciousness, for example, is noesis , while its intended object is the noema . Not only objects, such as an object of sense-perception, can be analysed in this way, but also acts of consciousness. The phenomenologist is not concerned, for example, with particular acts of sense-perception, but with the essential features common to all such acts. Moral and aesthetic values, and desires and emotions, are also open to phenomenological investigation. The phenomenologist must, on Husserl's view, perform an epoche , that is, suspend judgement, with regard to the existence of objects of consciousness.