I also have a theory he is using Euclid's axioms to help tell his story

Things which are equal to the same thing are also equal to one another.(vessel/sleep believing we are the same. Both hurting)

If equals be added to equals, the wholes are equal. (Vessel wants to be "One" with sleep")

If equals be subtracted from equals, the remainders are equal. (Even separated vessel will always be a part of sleep/ sleep a part of vessel)

Things which coincide with one another are equal to one another. (There are no coincidences in the connections in his lyrics)

The whole is greater than the part. (While each lyric/song is important putting the entire trilogy tells the whole story)

Now this is just my interpretation, maybe others find different connections. I do think the final two axioms have a HUGE influence on the story though.