The significance of a tritone?

[jancivil]

Another way to put this is, make a sonority out of Perfect Fifths:

C G D A E B F#; it's lush. I can end with a sonority like this, as very placid, actually.
(This is the fundamental reasoning underneath the Lydian Chromatic Concept, for the Lydian as more true than 'Major'.)

Even if you go all the way to 12, incl. C# G# D# A# E#, the basis in fifths vibrates a certain way.