Brotherhood or fraternity is of different kinds. It may be family association, the intimate relationship of the household. This is limited and subject to change and disruption. How often it happens that in a family, love and agreement are changed into enmity and antagonism. Another form of fraternity is manifest in patriotism. Man loves his fellow-men because they belong to the same nativity. This is also limited and subject to change and disintegration, as for instance when sons of the same fatherland are opposed to each other in war, bloodshed and battle. Still another brotherhood or fraternity is that which arises from racial unity, the oneness of racial origin, producing ties of affinity and association. This likewise has its limitation and liability to change, for often war and deadly strife have been witnessed between people and nations of the same racial lineage. There is a fourth kind of brotherhood, the attitude of man toward humanity itself, the altruistic love of humankind and recognition of the fundamental human bond. Although this is unlimited it is nevertheless susceptible to change and destruction. Even from this universal fraternal bond the looked-for result does not appear. What is the looked-for result? Loving-kindness among all human creatures and a firm, indestructible brotherhood which includes all the divine possibilities and significances in humanity. Therefore it is evident that fraternity, love and kindness based upon family, nativity, race or an attitude of altruism are neither sufficient nor permanent since all of 80 them are limited, restricted and liable to change and disruption. For in the family there is discord and alienation; among sons of the same fatherland strife and internecine warfare are witnessed; between those of a given race, hostility and hatred are frequent; and even among the altruists varying aspects of opinion and lack of unselfish devotion give little promise of permanent and indestructible unity among mankind.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 79)

For all beings are connected together like a chain, and reciprocal help, assistance, and influence belonging to the properties of things, are the causes of the existence, development, and growth of created beings. It is confirmed through evidences and proofs that every being universally acts upon other beings, either absolutely or through association.
(‘Abdu’l-Bahá, Bahá’í World Faith, p. 302)

Human brotherhood is likewise as clear and evident as the sun, for all are servants of one God, belong to one humankind, inhabit the same globe, are sheltered beneath the overshadowing dome of heaven and submerged in the sea of divine mercy.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 14)

Human brotherhood and dependence exist because mutual helpfulness and cooperation are the two necessary principles underlying human welfare.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 14)

In the creative plan there is no racial distinction and separation such as Frenchman, Englishman, American, German, Italian or Spaniard; all belong to one household. These boundaries and distinctions are human and artificial, not natural and original.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 23)

Is it possible for one member of a family to be subjected to the utmost misery and to abject poverty and for the rest of the family to be comfortable? It is impossible unless those members of the family be senseless, atrophied, inhospitable, unkind. Then they would say, “Though these members do belong to our family—let them alone. Let us look after ourselves. Let them die. So long as I am comfortable, I am honored, I am happy—this my brother—let him die. If he be in misery let him remain in misery, so long as I am comfortable. If he is hungry let him remain so; I am satisfied. If he is without clothes, so long as I am clothed, let him remain as he is. If he is shelterless, homeless, so long as I have a home, let him remain in the wilderness.” Such utter indifference in the human family is due to lack of control, to lack of a working law, to lack of kindness in its midst. If kindness had been shown to the members of this family surely all the members thereof would have enjoyed comfort and happiness.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 39)

We say “this man is a German, the other an Italian, a Frenchman, an Englishman,” etc. All belong to the great human family yet language is the barrier between them.
(‘Abdu’l-Bahá, Divine Philosophy, p. 143)

You are my family” and he looked about with a smile, “my new children! if a family lives in unison, great results are obtained. Widen the circle; when a city lives in intimate accord greater results will follow, and a continent that is fully united will likewise unite all other continents. Then will be the time of the greatest results, for all the inhabitants of the earth belong to one native land.”
(‘Abdu’l-Bahá, ‘Abdu’l-Bahá in London, p. 106)