When a person has his eye on the results of actions instead of being concerned solely with their intrinsic worth, he is trying to tackle spiritual problems through the mind alone and, in doing so, is interfering with the proper functioning of the heart. Mind wants to have all kinds of things and therefore seeks objective proofs, convictions, and assurances. This demand of the mind fetters the spontaneous outflow of love, which at once depends upon and furthers true spirituality. You cannot love through the intellect. What you may get through the mind is a theory of love, but not love itself. The kind of knowledge that certain types of yogis have attained through their minds is merely intellectual and dry. It cannot give them the spiritual bliss that characterizes the life of love.
Love and happiness are the only important things in life, and they are both absent in the dry and factual knowledge accessible to the intellect. Spirituality does not consist in intellectual knowledge of true values but in their realization. It is this knowledge of inner realization that is worthy of being called spiritual understanding, and this is far more dependent upon the heart than on the mind. Knowledge of the intellect alone is on the same footing as mere information, and being superficial, it moves on the surface of life. It gives the shadow and not the substance of reality. The hidden depths of the ocean of life can be gauged only by sounding the heart.
– Discourses 7th Ed. p96