In this process of the descent from above and the working it is most important not to rely entirely on oneself, but to rely on the guidance of the Guru and to refer all that happens to his judgment and arbitration and decision. For it often happens that the forces of the lower nature are stimulated and excited by the descent and want to mix with it and turn it to their profit. It often happens too that some Power or Powers undivine in their nature present themselves as the Supreme Lord or as the Divine Mother and claim the being’s service and surrender. If these things are accepted, there will be an extremely disastrous consequence. If indeed there is the assent of the sadhak to the Divine working alone and the submission or surrender to that guidance, then all can go smoothly. This assent and a rejection of all egoistic forces or forces that appeal to the ego are the safeguard throughout the sadhana. But the ways of Nature are full of snares, the disguises of the ego are innumerable, the illusions of the Powers of Darkness, Rakshasi Maya, are extraordinarily skilful; the reason is an insufficient guide and often turns traitor; vital desire is always with us tempting to follow any alluring call. This is the reason why in this Yoga we insist so much on what we call samarpana—rather inadequately rendered by the English word surrender. If the heart centre is fully opened and the psychic is always in control, then there is no question; all is safe. But the psychic can at any moment be veiled by a lower upsurge. It is only a few who are exempt from these dangers and it is precisely those to whom surrender is easily possible. The guidance of one who is himself by identity or represents the Divine is in this difficult endeavour imperative and indispensable.
Ref : The Mother with Letters on The Mother