Marc Peter Keane, adjunct professor of landscape architecture at Kyoto University of Art and Design, introduces the six main periods of interest in Japanese Garden design [KANSAI TIME OUT - MAY 1997]. The text is adapted from his book, Japanese Garden Design. Keane is also the co-editor of the recent translation of the Sakuteiki
http://www.japanfile.com/culture_and_society/history/Japanese_Gardens-1.shtml