Today is the 100th anniversary of the Easter Rising in Ireland. While I was writing my novel Stone Heart, Brendan Gill told me to reread "Easter, 1916" by Yeats. I thank him, and Yeats, for that, because the title was inspired by a line in the poem: "Too long a sacrifice can make a stone of the heart."
My family is Irish on both sides, and I grew up hearing that family members had fought that day. (Most Irish people seem to have heard that.) Maybe it's true. All I know is that the poem is true, and so is that particular line, not just in the context of Ireland, but in all human suffering. Peace and love.