Music won't tell you whether you should sing right now or play the lute, or do neither. What faculty will tell you? The one that can examine both itself and everything else. What is this faculty? Your reasoning mind. This is the only faculty we have that examines itself — what it is, what power it has, and what value this gift has. It also examines all other faculties. What else tells us that golden things are beautiful? Gold doesn't say it's beautiful. Obviously, it's the faculty that can judge what we see and experience. What else judges music, grammar, and the other faculties? What else proves their usefulness and shows us when to use them? Nothing else.
but whether you should sing at the present time and play on the lute, or do neither, music will not tell you. What faculty then will tell you? That which contemplates both itself and all other things. And what is this faculty? The rational faculty; for this is the only faculty that we have received which examines itself, what it is, and what power it has, and what is the value of this gift, and examines all other faculties: for what else is there which tells us that golden things are beautiful, for they do not say so themselves? Evidently it is the faculty which is capable of judging of appearances. What else judges of music, grammar, and the other faculties, proves their uses, and points out the occasions for using them? Nothing else.