I would highly recommend listening to any of his fugues. The great thing about them is you do not need any training to appreciate the complexity. All you need to do is listen to the starting melody.

That melody will repeat itself again and again, if you listen closely. It will harmonize with itself as more voices are added. It will be modulated into different keys and durations.

In a way, you can kind of think of Bach as the first electronic musician, in the sense that his works consist of "discrete tracks" that get layered on to each other. I'm sure there are youtube videos out there that demonstrate this visually.