Sri Aurobindo
Letters of Sri Aurobindo
Volume III - Part 1
Fragment ID: 12168
The periods of assimilation continue really till all that has to be done is fundamentally done. Only they have a different character in the later stages of sadhana. If they cease altogether at an early stage (you are still in a very early stage), it is because all the nature was capable of has been done and that would mean it was not capable of much.