Kindness is a virtue in many cultures and religions. The above picture is from a Laotian temple, depicting the parable of Buddha and the elephant Nalagiri. Devadutta, jealous of Buddha and wanting to hurt him, sends an angry elephant named Nalagiri into a street where Buddha and his colleagues were walking. As the angry Nalagiri approached them, Buddha's loving kindness and friendliness tames Nalagiri. The parable suggests kindness affects everyone. Buddhists call such kindness in virtuous state of perfection as Mettā, while some Indian literature refer to it as maitrī (Sanskrit: मैत्री).
According to Book Two of Aristotle's "Rhetoric" it is defined as virtue. It is defined as being "helpfulness towards someone in need, not in return for anything, nor for the advantage of the helper himself, but for that of the person helped".
Philosopher Friedrich Nietzsche argued that kindness and love are the "most curative herbs and agents in human intercourse".
In 2009, analysts warned that 'real kindness changes people in the doing of it, often in unpredictable ways. Real kindness is an exchange with essentially unpredictable consequences'.
They also argue that, in a relationship, 'real kindness, real fellow-feeling, entails hating and being hated - that is, really feeling available frustrations – and through this coming to a more real relationship'.
"Kindness is 'Pure Love' expressed / experienced / realized ~ 'Human Kindness' defines the fate of Humankind." Jaime Corpus Reyes, Waves Of Kindness Global Initiative 
It has been suggested that 'most of Shakespeare's opus could be considered a study of human kindness'.
Robert Louis Stevenson considered that 'the essence of love is kindness; and indeed it may best be defined as passionate kindness: kindness, so to speak, run mad and become importunate and violent'.
The Christian apostle Paul lists kindness as one of the nine traits considered to be the "fruit of the Spirit"  in Galatians 5:22.
^Harvey, Peter (2007). An Introduction to Buddhism: Teachings, History and Practices. Cambridge: Cambridge University Press. ISBN 0-521-31333-3
^Warder, A. K. (1970; reprinted 2004). Indian Buddhism. Motilal Banarsidass: Delhi. ISBN 81-208-1741-9
^Gonda, J. (Ed.). (1977), A History of Indian Literature: Epics and Sanskrit religious literature, Medieval religious literature in Sanskrit (Vol. 2), Otto Harrassowitz Verlag; see page 62 and note 43
^Aristotle (translated by Lee Honeycutt). "Kindness". Rhetoric, book 2, chapter 7. Retrieved 2005-11-22.[dead link]
^Nietzsche, Friedrich Wilhelm. "On the History of Moral Feelings," Human, all too human: a book for free spirits. Aphorism 48. [Original: Menschliches, Allzumenschiles, 1878.] Trans. Marion Faber with Stephen Lehman. University of Nebraska Press: First Printing, Bison Books, 1996.
^Adam Phillips & Barbara Taylor, On Kindness (London 2009) p. 12