We must be happy, for misery is the cause of jealousy which is the cause of all wars both big or small, but we must also be miserable – just ever so slightly, for madness is caused by irrational exuberance; so in the Rebbe’s words, we should be dancing that Moshiach is so close! But miserable (somewhat) that he isn’t here already! – and if we do this we will truly reach the height of human ability