巴哈欧拉的一个根本性的教导是人类世界的一体性。他这样忠告人类，“你们是一树之叶，一枝之果实。”这句话的意思是人类世界好比一株树，各国家民族是这树的不同枝干，而每个人象是这枝干上的果实和花朵。

                            （阿博都.巴哈，《世界和平之传扬》，p. 54）

“A fundamental teaching of Baha’u’llah is the oneness of the world of humanity. Addressing mankind He says, ‘Ye are all leaves of one tree and the fruits of one branch.’   By this it is meant that the world of humanity is like a tree, the nations or peoples are the different limbs or branches of that tree and the individual human creatures are as the fruits and blossoms thereof.”   

                  (By `Abdu’l-Baha, “Promulgation of the Universal Peace”, p. 454)