Sri Aurobindo
Letters of Sri Aurobindo
Volume IV - Part 2
The fact that the anger comes with such force is itself enough to show that it is not in you that it is, but that it comes from outside. It is a rush of force from the universal Nature that tries to take possession of the individual being and make that being act according to the will of this outside force and not according to the will of the soul within. These things come in the course 
of the sadhana because the sadhak is liberating himself from the lower nature and trying to turn towards the Mother and live in her divine consciousness and the higher nature. The forces of the lower nature do not want that and so they make these rushes in order to recover their rule. It is necessary when that comes to remain quiet within remembering the Mother or calling her and reject the anger or whatever else comes, whenever it comes or however often it comes. If that is done, then these forces begin to lose their power to invade. It is easier if one clearly feels them to be outside forces and foreign to oneself; but even if you cannot feel that yet when they enter, still the mind must keep that idea and refuse to accept them as any longer a part of the nature. The idea of the Mother being severe was of course a suggestion that came with the invading force so as to help it to enter. Such suggestions come to many sadhaks (though not so many as before) at Pranam and is the cause to them of much disturbance. Such suggestions must be firmly rejected at once.