What is it that maintains "ignorance of the self" more firmly than anything else? It is doubt, and doubt comes from the intellect, the thinking, discerning mind.
The mind wants understanding on its own terms. It easily confirms and acknowledges experience, but it needs its own form of proof to relax and let go. It may even dislike its own doubt, but if it is honest, it wants satisfaction on its own terms.
As a spiritual seeker, you may have had a number of epiphanies, intense, unitive, and ecstatic experiences. They may have come with immense authority beyond measure. And yet they ended. They disappeared and went away.
Where does that leave you? Satisfied? No! Now you have a huge mote between experience and intellect - a gulf that seems insurmountable. The intellect remains, but the ecstasy is gone.
Without the feeling intensity of the experience, the intellect doubts the validity of what was experienced. Without the authority of the experience in full bloom, the intellect feels bereft.
The intellect acknowledges the experience, but it cannot understand it. It does not have the feeling capacity of the experience. It is left, as in a wasteland, looking for the meaning and significance of the experience.
As you know, experience is often outside the realm of reason, and does not easily succumb to investigation. Doubt sets in and disturbs the mind greatly, with no end to the pain. Somehow the gulf opened up needs to be crossed.
To dispel doubt, the mind needs help. It needs a method to see, on its own terms, what was experienced. So how does the mind examine doubt? It needs to satisfy itself in its own field, with discernment, logic, and reason.
It needs to examine doubt in its own light.
If the cause of doubt resides in the intellect, then the answer has to be satisfactory to the intellect. It needs a means, a science, a method of investigation.
That means is self inquiry. And self inquiry requires brutal honesty, brutal logic, and brutal persistence. This inquiry has to be pursued with the intensity that was revealed in the experiences. Yet this inquiry must be done with the mind, the full participation of the intellect, so the end result is conclusive, without doubt, satisfying the mind.
The intellect needs to have the same degree of satisfaction from inquiry, that the feeling experiential side, of you, received from epiphanies and ecstasies. Where the epiphanies may have come uncalled for, self inquiry is work.
Knowledge via self inquiry takes effort. You have to show up, and you have to do the work. But, like any science, there is a history, and there are methods, and they can make the path straight and narrow. A good scientific method can save years of time.
The science of self inquiry, Advaita Vedanta, has been around for a long time. How many thousands of years is not really known, but it has proven its worth over these years, and it works today. It is not a belief system, nor a religion, but a systematic means with various techniques that can lead to the end of doubt and the end of seeking.
The term "enlightenment" came out of the ancient East where is was defined and refined. They honed the terms, the methods, the questions, and the pointers. They have left it to us in the Vedas. But it is up to each one of us to take up the inquiry and find the answer for him or herself.
The end of seeking may not be bliss, but it is peaceful, and it is satisfying. The force is with you.