Watch a documentary about how Sabbath started out. Mostly they had used old equipment and were broke. Then dig into their debut.. Consider the other groups who were topping the charts at the time. I heard from the doc I watched. that the british critics had a hay day with Sabbath and really put them through some shit. But thanks to the American listeners they took off and gained a huge following fan club. I consider their first to be one of the best studio albums they produced.