From Mencius 《
孟子·
告子下》: ‘
天将降大任于是人也,
必先苦其心志,
劳其筋骨,
饿其体肤…’ The mainland textbook tradition renders the third character as
斯; many classical editions have
是. Both readings mean ‘this / such.’ A famous debate broke out online in 2022 when people noticed the textbook wording differed from some printed classics — scholars confirmed
斯 is a well-attested variant.