Hey I guess I just wanted to post a lesson on Chord Cadences :P
(tell me how I did veterans)

First play the I chord followed by a leading tone (Usually a ii or IV when not given) then the Cadence

A Cadence is an urge to go to the I


Authentic Cadence -Best for a final "rest" in music

Perfect Authentic Cadence

V or V7 Leading to a I (Most Powerful Cadences

Imperfect Cadence

vii* (diminished) Leading to a I


Deceptive Cadence

a V or V7 or vii* going to a vi or vi7

or in Phrygian a iv6 going to a V


Half Cadence

A leading tone followed by a V chord and stop there

Plagal Cadence

A IV to a I (used in church music)

List From Most Powerful to Weakest Cadences
(you should be able to figure out what the letters stand for)

PAC Strongest
IAC
PC
DC
HC Weakest

There! :D

Good lesson. I forgot about how to do cadences. Deceptive Cadence is a cool one especially.

Hmm which one is used in a 12 bar blues?

I'm pretty sure its a Perfect Authentic Cadence

According to what I was told, there exist something called "Diabolus in music" which consist on going from the 4th degree of the major scale to the 7th degree (halfdiminished).

Can anybody give a good explanation of this?

That's the tritone, though it works with every degree of the scale.

The tritone is an interval of three whole steps, which equals to an augmented fourth and its enharmonic diminished fifth.

The interval was avoided in medieval music due to its dissonant sound (someone correct me if I'm wrong).

Yes, you're right. Although Medieval European music left out tritones, it been known that African used tritones at the time.