Corner is gold, Edge is silver, center is grass
Corner is gold, Edge is silver, center is grass (金角银边草肚皮) is a Chinese Go proverb. It means that territory in the corner is the easiest to surround, followed by the edge, and the center is the hardest place to get territory.
There exist various "proverbs" to a similar end, such as "There is no territory in the center", "The center is just dame", that overstate the case and elicit responses by fans of Takemiya Masaki and other notable centre-oriented players.
See also: Corners, then sides, then center