Alberto Martín has spent many years studying and practicing Christianity, Sufism, Buddhism, and Advaita Vedanta (in that sequence) plus, at one time, the religion of the Crows (a native tribe of N. America). "For me, it has been universalism all along ever since I read Plato when I was 15 years old. Lately my attention has been focused on Shankara's Advaita Vedanta and non-duality."
For this author, Plato and Shankara say practically all that can be said about reality and the way towards its assimilation and exemplification.
In this work Martín answers many of the probing questions anyone of us is led to ask along our lives.