Meditation, according to the spiritual meaning of the term, is not a process of the mind, but of the spirit. It goes through two stages: the preliminary one which can be defined as concentration, and the final one which can be called contemplation. Contemplation consists of gathering our attention with devotion in God, and raising it to one’s own focal Center in the body. Mystics, Saints and Masters call this Center with different names. Christ calls it the single eye (aplus in the Greek text, Mathew 6:22) and St. Agustin calls it the “eye of the soul” (Confessions 7:10), while in the East it is called the third eye, or “tenth door” in order to distinguish it from the nine openings of the body (eyes, ears, nostrils, mouth and the two lower openings) tied to the plane of the senses.
With the awakening of the “eye of the soul” or inner eye, the human soul may contemplate the Light of God, an experience which is common to the major mystics and Saints, both Christians and non-Christians of the East and the Middle East. Thus all the Scriptures affirm that God is Light. Saint Agustin and many other Saints actually speak about the manifestation of God as Light.
The human soul also has an inner ear with which it can tune into the Divine Power or Word vibrating in the entire creation, the sacred creative Sound. The Divine manifestation (or Holy Ghost), in the two forms of Celestial Light and Sound, was experienced by the Apostles at Pentecost (Acts 2:2-4).
Our body and the physical plane are important only because they are the dwelling of the soul: through them one must find the Way upwards by knowing oneself first and then the Divinity. Your answer to the question about existence and the need to turn within is therefore exact, and it is a bit the summary of the teachings of all the great Masters of the spirit that have come from time to time in different places.
Obviously the knowledge of oneself as indicated by the Masters is not of a physical or mental nature since the real Self is the divine spirit that lives in every living being. Also the means for knowing the Self can be none other than the one of spiritual nature. The meditation handed down by the Masters from remote epochs which has reached us with their grace consists in contemplating the inner Light and listening to the sacred omnipresent Sound, the two manifestations of God Power in expression, in order for the human soul to have the ability to “see” and “hear”. This is also called the Holy Ghost, Word, Naam, Shabd, etc., by the different Scriptures.