There's much more acoustic guitar (Orchid and Embryo) and sometimes a darker and heavier sound in this third album by Black Sabbath. I find Master of Reality is more polished and blunt than other their albums, but the most incredible thing is that it was published subsequently to albums like Paranoid and Black sabbath, two incredible works; Master of Reality is no less potent that the first two. Highlights are Into the Void, Children of the Grave and Sweet Leaf.