If you want to astral travel at will you need only listen to what occult,etheric techniques I have had need to practise to get access to realms and planes ofpsychic dimension. Dimensions where my 'subtle spirit' or altered state, could travel, half consciously one might say, using a system simply based on dreaming leading to psychic-separation by way of trance into worlds where gross existence falls away and one becomes comfortable without a body--the obe some call it--an illusion others call it--I call it psychic travels by way of learning focused meditation.