Today is the first I ever heard of "discovery" in relation to alchemy (or any of the professions for that matter). What is it, how does it happen, and how do you know when it happens? do you get a post that says "You have just discovered how to make elixor of cowards." or some such nonsense, or does it just show up in your recipe list? I have recipes that I don't remember learning but I figured it's just because I bought it off the auction house at a higher level and never made it. Does this happen with any other proffession? Please enlighten me.

After making a potion or xmute, you see a flash, much like when you level or rep up and in the chat box it says....Discovery, You have just discovered how to make flask of coolness.  After which it appears in your recipe book.  Of the three I've now learned one was lettered grey at the time, one is yellow and one red.  I'm am a 375 alchemist, so I assume the red one is the most rare of the three.