」夫剛則不和，不和則不可用。
Hard things, let us note, do not accord well with other things; and what does not accord well with other things cannot be used.
是故四馬不和，取道不長；父子不和，其世破亡；兄弟不和，不能久同；夫妻不和，家室大凶。
Thus, when a team of four horses lack concord, they will not go for a long distance; when a father and a son lack concord, their lineage will suffer destruction; when elder and younger brothers lack concord, they cannot live long together; and, when married couples lack concord, great evil will overtake their families.
易曰：「二人同心，其利斷金。
」由不剛也。
As is said in the Changes, ‘When two people are of one heart, their keenness will be sufficient to break metal.’27 Such concord arises from not being hard.