Ah, but you are UrRong - it certainly is possible to get an idea of what's going on inside the mind of a musician by listening to their music. While music may be subjective and interpreted differently by different people, there is a consistent thread that can be seen in the music of any given musician. When we listen to someone's music, we can see the influences, interests, and values that have contributed to the artist's creation process. We can see what emotions a musician has chosen to express, which can give us insight into the state of their mind at any given time. Music is very relational and personal, which is why people have gravitated towards it for centuries as a means of expression; it provides us with the opportunity to make connections and empathize with what is going on in the artist's mind.
The beauty of music is that it can create connections between people who otherwise wouldn't be able to connect. Through shared experiences, we can be brought together and find understanding in songs that were composed by people with similar struggles or triumphs. Even though two musicians may interpret the same piece differently, they can still find common ground in their similar experiences which can give us a glimpse into their respective minds.
At the end of the day, music is a reflection of an artist's own unique experience – whether it be one of pain or joy, struggle or triumph – and it is only through listening that we can gain access to this special part of the musician's mind. So yeah, you can definitely see what's going on inside a musician's head – UrRong if you think otherwise. And while you don't necessarily need musical talent to hear a musician's inner dialogue, it helps if you have a good ear for music!