Assimilation

Why does the body get tired? We have more or less
regular activities, but one day we are full of energy and
the next day we are quite tired.

Generally this comes from a kind of inner disequilibrium. There
may be many reasons for it, but it all comes to this: a sort of
disequilibrium between the different parts of the being. Now, it
is also possible that the day one had the energy, one spent it too
much, though this is not the case with children; children spend
it until they can no longer do so. One sees a child active till
the moment he suddenly falls fast asleep. He was there, moving,
running; and then, all of a sudden, pluff! finished, he is asleep.
And it is in this way that he grows up, becomes stronger and
stronger. Consequently, it is not the spending that harms you.
The expenditure is made up by the necessary rest—that is set
right very well. No, it is a disequilibrium: the harmony between
the different parts of the being is no longer sufficient.

People think they have only to continue doing for ever what
they were doing or at least remain in the same state of consciousness,
day after day do their little work, and all will go
well. But it is not like that. Suddenly, for some reason or other,
one part of the being—either your feelings or your thoughts
or your vital—makes progress, has discovered something, received
a light, progressed. It takes a leap in progress. All the
rest remains behind. This brings about a disequilibrium. That is
enough to make you very tired. But in fact, it is not tiredness: it is
something which makes you want to keep quiet, to concentrate,
remain within yourself, be like that, and build up slowly a new
harmony among the different parts of the being. And it is very
necessary to have, at a given moment, a sort of rest, for an
assimilation of what one has learnt and a harmonisation of the
different parts of the being.