This Maxim is NOT telling us that we need to know every judge on the bench ‘just in case’ we get in front of them. It is telling us that we need to understand our inner judge. We need to know and understand the part of ourselves that makes judgment calls so that we can understand that part of other people.
We judge everything, whether we wish to or not. And it is because of this that we need to understand the standards by which we measure things. Is something good or bad, proper or improper, pious or blasphemous? All of these things are value judgments and we need to understand our values before we can truly make these calls. For whether we wish to be or not, we ourselves are the ‘first’ judge of our actions, our words, and even our thoughts. It is only after we have spoken or acted that other people will judge those words and deeds.
How will they judge them? Their own inner judges will be the way that they evaluate our words and deeds for their merit – and how they either find them praiseworthy or unworthy. This is the judge we must know and this is the judge that the Maxim speaks of.