Is it the mind that sets limits on man?
The desiring mind in man sets limits on everything - whether it is something that he already has or something that he wants to possess. But the aspiring heart in man deals with the infinite - with things that are already infinite or things that eventually will be infinite. When someone lives primarily in the mind or in the desire-world, he is enchained by the limitations of his mind. When the same person enters into the world of the aspiration, that means he wants to liberate himself from the world of limitations.
Can a seeker live in vast expansion of mind, or is this possible only for a realized soul?
Vast expansion of mind the aspirant can have for a few minutes when he is in a very high, deep meditation. Only the realized soul can enter into this vast expansion of mind and stay there indefinitely. But we are actually making a mistake when we use the term "expansion of the mind." In the state I am referring to, there is no mind; the mind has been transcended. We feel that what we experience is the expansion of the mind, but it is actually the transcendence of the mind. In the mind there is form, there are limits; but when we speak of the vast expanse, it is something beyond the domain of the mind. It is a vast expanse of Light, consciousness, peace, and bliss.
When we are meditating, we always try to go beyond the mind. When we want to expand our consciousness, our physical reality, we have to enter into the soul. But when we come back from the highest level of consciousness, we try to understand and express the state we were in with the help of the mind. That is because the mind right now is the highest product of human life. But because the mind is limited, it can never understand and express the infinite, the Unlimited.