The imagination stops building aircastles, or running off on foolish lines;
他的思想不再会建造空中楼阁，也不再会追逐无智的事物了；
2
As he walked along, his brain was busy planning hundreds of wonderful things, building hundreds of castles in the air.
当他走着的时候，他的脑子里正忙着计划许多奇妙的事情，建起一座座空中楼阁。
3
Americans have been living high on borrowed money (the savings rate dropped from 7.6 percent in 1992 to less than zero in 2005) while financiers built castles in the air.