Tortoise: Something is very wrong. This record is a disgrace to the world of music.

Achilles: What do you mean?

Tortoise: It was exactly what I was telling you about. Here Bach had modulated from C into G, settting up a secondary goal of hearing G. This means that you experience two tensions at once–waiting for resolution into G, but also keeping in mind that ultimate desire–to resolve triumphantly into C Major.

Achilles: Why should you have to keep anything in mind when listening to a piece of music? Is music only an intellectual exercise?

Tortoise: No, of course not. Some music is highly intellectual, but most music is not. And most of the time your ear or your brain does the “calculation” for you, and lets your emotions know what they want to hear. You don’t have to thinkg about it conciously. But in this piece, Bach was playing tricks, hoping to lead you astray. And in your case, Achilles, he succeeded.

Achilles: Are you telling me that I responded to a resolution in a subsidiary key?

Tortoise: That’s right.

Achilles: But still sounded like an ending to me.

Tortoise: Bach intentionally made it sound that way. You just fell into his trap. It was deliberately contrived to sound like an ending, but if you follow the harmonic progression carefully, you will see that it is in the wrong key. Apparently not just you but also this miserable record company fell for the same trick– and they truncated the piece early!

Achilles: What a dirty trick Bach played on me.

– De los freaky diálogos de Aquiles y la tortuga de Gödel, Escher and Back: An Eternal Golden Braid.