To sign away his rights to the book would have been the height of folly.他签字放弃著作权真是愚蠢之极。It is the height of folly and a tragic waste to gallop into war.仓促发动战争是极其愚蠢的行为，是一种可悲的浪费。It would be the height of folly for us to accede to their unreasonable demands.如果我们同意他们的不合理要求，那将是愚不可及的。