Baha’u’llah “likened this world of being to a single tree, and all its peoples to the leaves thereof, and the blossoms and fruits”

The Blessed Beauty saith: ‘Ye are all the fruits of one tree, the leaves of one branch.’ Thus hath He likened this world of being to a single tree, and all its peoples to the leaves thereof, and the blossoms and fruits. It is needful for the bough to blossom, and leaf and fruit to flourish, and upon the interconnection of all parts of the world-tree, dependeth the flourishing of leaf and blossom, and the sweetness of the fruit.

For this reason must all human beings powerfully sustain one another and seek for everlasting life; and for this reason must the lovers of God in this contingent world become the mercies and the blessings sent forth by that clement King of the seen and unseen realms. Let them purify their sight and behold all humankind as leaves and blossoms and fruits of the tree of being. Let them at all times concern themselves with doing a kindly thing for one of their fellows, offering to someone love, consideration, thoughtful help. Let them see no one as their enemy, or as wishing them ill, but think of all humankind as their friends; regarding the alien as an intimate, the stranger as a companion, staying free of prejudice, drawing no lines. 

- ‘Abdu’l-Baha  (‘Selections from the Writings of ‘Abdu’l-Baha)