Because there are no lyrics and prominent vocal lines to hook your attention, they’re an ideal aid to focus on work, or a workout, or unwinding after either of the above, or indeed hosting a dinner party or any other social occasion that needs some (but not too much) musical accompaniment. The best instrumental albums, which congregate especially in genres like jazz, ambient, electronic and post-rock, contain as much depth as any vocal music; you can sit back and just listen to them, and be properly rewarded for your attention. Journey in Satchidananda – Satchidananda being an Indian guru Coltrane had studied under – is a potent, transcendent record, with Indian instrumental flavours complementing the more Western jazz elements.