This post is part of a series about the modes.
Aeolian is the same as the natural minor scale or the white keys from A to A. To play this mode starting on a different note, just play natural minor.
So how to talk about a mode that is now one of our regular scales? Doesn't it work just like minor? Well yes. And no. It is actually quite common for today's minor music to use a raised 7th at some point (relates to the harmonic and melodic minor scales) to get the sound of the raised 7th leading to the tonic. Aeolian does not have this sound. Since a great deal of modern music theory worries about how the 7th (and other notes) lead to the tonic, this is actually a bigger difference than you might think. Just to give you an idea of how big, musicians were beginning to use raised 7th sounds back in the Middle Ages and Renaissance, before major and minor quite existed. A ridiculously popular tune (then and now), "Greensleeves," is actually half in the modal Aeolian and half in the more modern minor (the end of the phrases is where the raised 7th sound sneaks in.) Not that they thought of it that way of course. They were just living in a time in-between the modes and the major-minor systems and their music showed it.
Aeolian can sound oddly plain to people who are used to the major-minor system. The notes stay the same no matter what is happening in the final cadence. This means the harmonies don't always match the music theory worked out for the major-minor system and so once again we have to work with this scale on its own terms. For starters, we have to understand that there won't be as much pull to the tonic (the starting and ending note) from the 7th note as we are used to. In Aeolian, landing on the tonic from the 7th note is more of a surprise, or a push, than a pull. It isn't always as final sounding as you might think either but that leaves some room for ornamenting a couple of last frills and turns that you can't always get away with in today's minor music. And that is what I like about Aeolian. It gives you room to be ornate and flashy even with a simple melody. Maybe especially with simple melodies. Of course, it is possible to go overboard with this and make the end of the piece circle in on itself in an endless loop that makes your audience start looking at their watches. This makes ending pieces in Aeolian a slippery business. One trick is to segue from Aeolian to Ionian (basically major) to keep from getting lost in the final cadence maze. This actually happens in folk music quite often as major (Ionian) and minor (Aeolian) tunes are paired up and played together as a single "piece." And Classical music often does exactly the same thing by having minor and major movements following each other in a piece.
Since most people automatically think of minor as being sad, it would make sense for Aeolian to be used for slow pieces. Which it is at times, but in folk music it is actually very common to find fast dances, like jigs, that are in Aeolian. Something about the contrast of the closed sound of this scale with the speed and jumping rhythms works beautifully together. My personal theory is that the Aeolian scale keeps the fast upbeat music from getting so cheerful we can't stand it. We get to be happy but don't feel like we are being drowned in sugar.
I look at Aeolian as one of the best places to start working with modes. It is possible to move from Aeolian to other modes fairly easily since we, as modern listeners, are used to minor shifting about quite a bit. And it is a great mode for learning to handle ornaments, extended endings and in general breaking out of our modern major-minor musical mind-sets. It is an extremely friendly mode.