The sacrifice refered to with regard to Sri Aurobindo’s physical withdrawal is the renunciation of the realisation in his own body so that the collective realisation can be hastened. It is like someone sacrificing his own life so that his country wins the battle. This was needed to counterbalance the unconscious and darkness in humanity. The sacrifice of a Divine being creates a sudden vacuum upon earth to fill which Divine forces from the higher worlds rush in from above touching humanity and force opening a door within them. The consciousness of the sacrificient Yogi, freed from the body gets universalised and thereby helps and uplifts humanity. You will find more details on talks on this subject on auromaa.
Affectionately,
Alok Da
