Bergson said "the spirit embraces the past, while the body is confined in a present that constantly begins again and again". Indeed, our mind handles content that come from the past but it works organically in the pure present, which is constantly renewed independently of those memories. All true operation, mental or of any kind, necessarily occurs in the present...
We do not perceive the present in a pure way, we can only to intuit; it is a hidden variable to our direct knowledge and we just can make suppositions, because all perception is contaminated by traces of the past, by the knowledge we have been setting over time. Memories shape our perception of objects and events that occur now. However everything real occurs now, in 'a present that continually starts again and again' and in which we are confined. It seems a terrible paradox.
The present is the duration of the phenomena, the duration of the actions of our body and our perceptual and cognitive systems. The present is biology. Any activity of our body is hopelessly confined to it. It is an unstable, shifting, biology, made of events and actions, which makes change our psychology beyond the mental contents and their associations in memory. The variable physiological activity that underlies the mind is pure action and succession, while the mind, subjective result of such succession, is a continuous recreation of the past, is an invention of the past from an organic mind that although we sense it, we do not know it.
Physical activity of mind, with its own variations, is not encodable to mind itself, it is not perceptible as mental content that has to be fixed in memory, although it is 'perceived' many times in a sensory level and in a high degree. The physiology behind the mind does not enter into its own electrophysiological circuits as content, since it is what sustains them, gives them energy, makes vary, work and flow them. No activity by itself can to represent itself; something like that simply can not exist.
This is a totally animal primary reality, that just happens, without logic, and that makes you feel subjective states and which unfolds, yet now, the logic of the contents of your mind. This dyes that contents, modulates them, but is not one of them. These variable physiological states affect all mental functioning, memory, thought, emotions but are not assimilated as content. They break the rules of the association of ideas. Do not work as memory traces or contents or thoughts, can not be integrated into the informational circuits. But we feel them and they affect the whole. They are much more primary, are the price we pay for being biological organisms, for being alive; they are the specificity of our biology. They are the 'elan vital', the 'vital force'. They are what always will differentiate us from the most sophisticated machine that can ever exist.