Freakin' awesome. I learned about Flavin from watching PBS's Art21 series. (If you aren't already familiar with this series, I highly recommend it.) These pieces are incredible. I love how such a distilled combination of light and color and space can still evoke such powerful feelings. Just incredible.
(images via the Tate, Pacific Standard, Grammar Police, Asymptotia, David Byrne, and axmk.com)