I'm reading a book where the augmented 3 interval(two note) is considered a dissonant. However being that its enharmonic equivalent is a perfect fourth, I can't see how this can be so.
I've done a little digging and some say that it has to do with the context of the music. So I'm presuming that if perhaps a composer for example drifted into a different mode/scale he may spell the perfect fourth interval as a Aug 3rd (and therefor a dissonant) in this new context. Depending of course on the scale.
So for example this interval would be written in as a Aug 3 if the composer was writing in c lydian; the e sharp clashing with the f sharp of the lydian mode.
Am I right in this thinking