Ok, I'm a little perplexed about something and I'm hoping someone can shed some light on this for me. I'm really hard pressed to come up with a clean and coherent way to explain this so please bear with me here while I try to ramble all of this out. I've been doing some experimenting lately with scales and modes. Basically I've been looking to expand my knowledge of harmonic possibilities, I'm not sure if how I am going about it is actually productive though? At this point I'm just jotting down facts for future reference as I come across them. This really isn't a part of my basic practice routine, just stuff I'm doing in my spare time. Yeah, I have no life. Take the follwing scale for example: Ab - Bb - C - D - Eb - F - Gb - Ab W - W - W - H -W - H - W It's clear that this is an Ab Lydian Dominant scale. Now if I understand things correctly this specific scale would commonly be described as a the 4th mode of Eb Melodic Minor? While messing around with modes of other scales I realized that this scale also appears as the 6th mode of C Half-Diminished scale. Maybe in other places too but I haven't found them yet. Another example would be that the diminished whole tone scale/chord is 7th mode in Melodic Minor Harmony, it's also the 2nd mode of Half-Diminished Harmony. I never hear it refered to as such though, I figure there must be a good reason. I hope that makes sense...I have a feeling I'm missing a vital point in all of this. I'm posting this because it feels like I'm stumbling on to something important here by doing what I am doing to come up with conclusions like this, but what the heck am I actually doing? And is it really important to be able to see things this way? Are the angles that I'm exploring actually gonna help me if I ever catch a glimpse of the big picture that is harmony. Most importantly, am I making any sense at all here. I can see clearly how it is important to be able to see/hear a F Lydian Chord and know that it a IV chord in the key of C, and that the F Lydian scale would be an appropriate choice of notes to work with if I want to stay inside. Basically what I mean is to have a working understanding of fundamental harmony. Ok, I'm spent now. I really don't know how to further discribe what is going on in this little warped brain of mine. Hopefully one of you can bring some perspective to this for me. Thanks for taking the time to read all of this.  There's nothing more I hate than screwing up the title of a thread. I really gotta stop posting on message boards in heavily sleep deprived states...ughh.