And it requires sanctity, separations, purity, and a pure heart in the pursuit of truth, the pursuit of justice and peace, the pursuit of knowledge with love of God and fear of Him, and the grasp of wisdom and true understanding that are hidden in order to merit it. Anything other than this is dangerous, as the cause of harm is based on unacceptable free speculation, as the Ramban stated in the introduction to his commentary on the Torah, and it is detrimental to a corrupted soul. It is a snare. All of this is already known in the books of the Kabbalists. Whoever wishes to know on what their foundation is based should study them and find sufficient certainty. Therefore, I will not dwell on this, as assisting without strength, etc., is futile.
Ramban Studies Torah
Mitpachat Sefarim 1:44