The 13th-century Japanese master Eihei Dōgen asserted in the Shōbōgenzō that a day consists of 6,400,099,180 moments (which make a moment about 1/74,000 of a second). In Each Moment is the Universe (2007), Zen monk Dainin Katagiri writes that these moments are so fleeting that our rational minds are too slow to keep up with them, and so we experience a gap between us and the reality of time, which is why we feel we can't keep up, and why we suffer. According to Buddhist teaching, everything exists together in a moment.
The past has already gone, says Katagiri; so it does not exist. The future has not yet come; so it also does not exist. So the past and the future are nothing, no-time. Then is the present all that exists? No, even though there is a present, strictly speaking the present is nothing, because in a moment it is gone. So the present is also nothing, no-time, no-present, no form of the present.
But that nothingness is very important. The real present is not exactly what you believe the present to be. In everyday life we constantly create some idea of the the human world is because we are always thinking about how things were in the past or how things will be in the future. The real present is the full aliveness that exists at the pivot of nothingness. Be present, Katagiri says, from moment to moment, right in the middle of the real stream of time.
In the Shōbōgenzō Dōgen says that when you swim on the surface of the sea, your foot touches the bottom. The surface is the "normal" human world in the stream of time, the world we create with our imagination, memory, and hopes, while the bottom is the reality of human life. So the surface is constantly changing, but the bottom is the firm reality, and we always swim with one foot on the bottom.
It takes on average half a second for the unconscious mind to process incoming sensory stimuli into conscious perceptions. Yet we are not aware of this time lag — you think you see things move as they move, and when you stub your toe you get the impression of knowing about it right away. This illusion of immediacy is created by an ingenious mechanism, which backdates conscious perceptions to the time when the stimulus first entered the brain.
On the face of it, this seems impossible because cortical signals take the same "real" time to process to consciousness, but somehow we are tricked into thinking we feel things earlier.
One wayit might be explained is that consciousness consists of many parallel streams and that the brain jumps from one to another, revising them and redrafting them.