First we must suspend our belief in an objective time outside of our experience. Some have claimed that time is not real, that it is an illusion, "maya." Other's say time is different for schizophrenics than for the rest of us. But how time is for others, or how it is in itself, or whether it exists at all are questions we leave aside by performing the Phenomenological reduction. Even after this suspension, we still find time in our experience, "inner time" or "internal time consciousness," and this is the time whose essence Husserl sets out to describe.
Secondly, we must suspend scientific theories of time. Many assume that time is what is measured by clocks, that it goes on objectively at the same rate whether observed or not. Newton thought of time as an absolute quantity, a measurable attribute of God's sensorium. Einstein says that time is a fourth dimension, mathematically similar to the other three, but relative in its quantity to the velocity of observers. Hawkins says that time starts with the big bang and was hugely accelerated during the first seconds of the universe. The phenomenologist, without denying any of these theories of cosmic, external or objective time, suspends belief in them in order to be able to achieve a pure description of how time is actually given to us in our experience.
Finally, and this is by far the most difficult, we must suspend all philosophical theories about the nature of time and of temporal experience.
Hume, for instance, like Husserl, claimed to start from experience. He claimed that each moment of experience involved a set of isolated (sense-) impressions. This too is an unsupported dogma, for Husserl points out that we don't in fact experience impressions. Hume claimed to be an empiricist, but was prejudiced by a philosophy of atomism and failed to actually do the hard work of looking at experience itself.
Hume's error is actually based on a more crucial prejudice which he inherited from Descartes. Descartes presents his cogito as a momentary experience valid only for the instant. Every moment of conscious life is an isolated, separate event, unrelated to the past and the future except by the creative power of God. Nothing in the present state of our consciousness intimates anything about the future, even that there is one. The world is created anew every moment by divine miracle.
In Descartes' own words, "a lifespan can be divided into countless parts, each completely independent of the others, so that it does not follow from the fact that I existed a little while ago that I must exist now ... For it is quite clear to anyone who attentively considers the nature of time that the same power and action are needed to preserve anything at each individual moment of its duration as would be required to create that thing anew if it were not yet in existence." (Meditations, no. 3)
Descartes seems to conceive of consciousness as a point, unextended in time as in space, relying on external factors such as bodily memory or divine intervention to relate to the past and the future. I suspect this notion of consciousness depends upon Plato's notion that the soul must be absolutely simple and unified. Descartes' mind seems to be modeled on his notion of an absolutely simple, and so eternal, God, who can grasp things in their unity because she is herself without any dispersion, either spatial or temporal. I will call this, our most misleading, prejudice, "the dogma of punctual consciousness." Husserl says we must not assume without investigation that consciousness is restricted to a durationless now. Don't assume, look and see!