Henri Bergson was a French philosopher (1859-1941) and one of the most influential thinkers of the 20th century. His philosophy revolves around motion, change and evolution.
His work in Time and Free Will: An Essay on the Immediate Data of Consciousness showed the fundamental difference between time as perceived by consciousness (la durée or duration) and the objective mathematical time read on a watch. Consciousness doesn’t perceive the instant or the objective present, for it is infinitesimal. It perceives a duration which can be very long or very short.
For example, if I am working unwillingly for one hour on my blog, time doesn’t fly. On the contrary, if I love what I am doing on my blog, I will not feel the time passing by. Although, the time, in both cases, is one hour and the same according to the watch, I live it, thus perceive it, differently.
Bergson analyzed the awareness that man has of his inner self to show that psychological facts are qualitatively different from any other, charging psychologists in particular with falsifying the facts by trying to quantify and number them.
Based on this analysis of the subjective time versus the objective time, he somehow criticized Albert Einstein for keeping the theory of relativity external to the human mind without taking into consideration one’s inner perception of the time, which is also relative.
Consciousness is memory and therefore a link between past and future through its duration. This empirical complexity is what makes human free beings, forever preserving the past and anticipating the future.