What in brief is the means to know one’s own real nature? What is the effort that can bring about the sublime inner vision?
Sri Ramana Maharshi:
Strenuously withdrawing all thoughts from sense objects, one should remain fixed in steady, non-objective [ie. subjective] enquiry. This, in brief, is the means of knowing one’s own real nature; this effort alone bring about the sublime inner vision.
Sri Ramana Gita, Chapter 3, verses 4-6
For a more detailed description of the path to liberation see here: The Path of Sri Ramana