To think of second and third persons is sheer foolishness, for by thinking of second and third persons the mental activities (mano-vrittis) will wax.
Attending to the FIRST PERSON ("I") is equal to committing suicide, for only by enquiring into the first person will the ego itself die.
-- 'Atma Vichara Patikam', verse 7
Taken from The Path of Sri Ramana - Part One (p112) by Sadhu Om
The import of thinking of "second and third persons" implies meditating on the body, breath, or external objects, concepts, thoughts. "First person" indicated the "I" / the awareness / the consciousness.
(Incidentally the new Ramana Maharshi website is this address: http://www.sriramanamaharshi.org/)