Someone once asked the Baal Hatanya zy’a what the Baal Shem Tov added by establishing Torah Hachasidus. Didn’t we already have Sefarim Hakedoshim, such as the Shlah and Reishis Chochmah? Weren’t there many big tzadikim even before the Baal Shem Tov?
The Baal Hatanya answered, ‘A homeowner has two ways to protect his home from thieves. The first way is that when he sees a thief in his yard, he can start to scream, and thereby scare him away. The second way is to let the thief enter his house so that he can catch him and hand him over to the police.’
‘If one uses the first method, the thief will run away, but he may return one day. But if he uses the second method, the thief will be imprisoned and he will not return. However, only a strong and smart person who is able to catch the thief can use the second method.’
‘Until the Baal Shem Tov’s days, the Sefarim Hakedoshim used the first method. They screamed that something is an aveirah, which led people to chase the sin away. The way of the Baal Shem Tov was to catch the sin and lock it away. That is the way that works best.’