You need to do that to be able to control the shield that's as big as that and as heavy as that, because it is made fundamentally of a heavy wood, typically covered by leather, sometimes with some bronze, a bronze sheet across the front of it as well.

如果你想自如操控这块盾牌就必须得这样,这种盾牌很大并且很笨重,因为它主要是由沉重的木材制成,表面一般覆有皮革,或包上铜皮,就是表面上有一层铜皮

耶鲁公开课 - 古希腊历史简介课程节选