Patterns + Motion = Potion (patterns in motion)

In Renaissance polyphony vertical arrangements of notes were put together according their consonance or dissonance above the lowest sounding notes. Masters of the late Renaissance handled vertical dissonances with special care. Since the idea of tonal harmony was as of that period, unknown, it is safe to assume that composers thought only in terms of consonances and dissonances.  Back then, the dissonant intervals were the P4, M2, m2, M7, m7 and any diminished or augmented intervals. Today you wouldn't even be dared to name a dissonant interval.  

 In the 19th century the 7th, 9th, 11th and 13th chords as well as augmented 6th chords (german 6th etc.) began to be used quite frequently. There in the Romantic age composers such as Chopin, Schumann, and Wagner started leaning toward heavier uses of accented dissonances and these dissonanances were sustained for much longer periods of time than their resolutions were held.

 

Although by no means a thorough one, the following table can be printed and used as a reference towards a better understanding of dissonances:  As music moves through time horizontally represented by the notes on a musical page.