Kindness is a behavior marked by ethical characteristics, a pleasant disposition, and concern for others. It is known as a virtue, and recognized as a value in many cultures and religions (see ethics in religion).
- 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".
- Kindness is considered to be one of the Knightly Virtues.
- According to eighteenth century Bohemian philosopher Honza z Žižkova, kindness is the most important part of his practical philosophy on deceiving bureaucracy.
- In Meher Baba's teachings, God is synonymous with kindness: "God is so kind that it is impossible to imagine His unbounded kindness!"
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'.
- The Tirukkuṛaḷ, an ancient Indian work on ethics and morality, dedicates a separate chapter on kindness (Chapter 8, verses 71-80), furthering the value in other chapters, such as hospitality (verses 81-90), uttering pleasant words (verses 91-100), compassion (verses 241-250), vegetarianism (verses 251-260), non-violence (verses 311-320), non-killing (verses 321-330), and benignity (verses 571-580), among others.
- "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'. Stevenson brought up an interesting thought; however, some argue that the essence of kindness is love. This argument stands on the grounds that love breeds other virtues such as goodness, self-control, and kindness.
- The Christian apostle Paul lists kindness as one of the nine traits considered to be the "fruit of the Spirit"  in Galatians 5:22.
In October 2011, Life Vest Inside posted a video called "Kindness Boomerang". Masterfully shot all in one take, it shows how one act of kindness passes seamlessly from one person to the next and boomerangs back to the person who set it into motion. It avoids being merely sentimental through the expert execution, and even achieves a strange power—packing more authentic human emotion into its five minutes than most corporate advertisers manage in a year or more. Kindness Boomerang was shot on September 1, 2010. Orly Wahba, Life Vest Inside Founder and Director of Kindness Boomerang explains that each scene was based on real life experiences she personally went through; moments of kindness that left a lasting impression on her life.
Within several months after its release, Kindness Boomerang went viral; reaching over 20 million people globally and eventually landing Wahba spot on the TED2013 stage to speak about the power of kindness. Kindness Boomerang sparked what has come to be known as the Kindness Revolution; an increased awareness and consciousness that each person matters and that kindness is within our reach.
Pay It Forward: Based on the novel of the same name written in 1999 by author Catherine Ryan Hyde, the motion picture Pay it Forward, which starred Kevin Spacey, Helen Hunt, Haley Joel Osment and Jon Bon Jovi, illustrates the power one person can have to impact a chain reaction of kind deeds. The philosophy of Pay It Forward is that through acts of kindness among strangers, we all foster a more caring society. In the book and film, Reuben St. Clair, a social studies teacher in Atascadero, California, challenges his students to "Change the world". One of his students, Trevor, takes the challenge to heart. As he goes about his day, he wonders what he could do to change the world. He starts by showing kindness to a stranger which ripples further than he could have ever imagined.
- 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's Rhetoric: Book II - Chapter 7
- Aristotle (translated by Lee Honeycutt). "Kindness". Rhetoric, book 2, chapter 7. Archived from the original on December 13, 2004. Retrieved 2005-11-22.
- 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.
- The Manual of Life - Character
- What is Kindness?
- Kalchuri, Bhau (1986). Meher Prabhu: Lord Meher, 11, Myrtle Beach: Manifestation, Inc., p. 3918.
- Adam Phillips & Barbara Taylor, On Kindness (London 2009) p. 12
- Phillips, p. 94
- Tirukkuṛaḷ verses 71-80
- Pope, GU (1886). Thirukkural English Translation and Commentary (PDF). W.H. Allen, & Co. p. 160.
- Waves of Kindness
- Lagrette Tallent Lenker, Fathers and Daughters in Shakespeare and Shaw (2001) p. 107
- robert Louis Stevenson, Virginibus Puerisque (London 1909) p. 35
- Galatians 5:22, New International Version
- "Kindness Boomerang". YouTube/Life Vest Inside. Retrieved 14 January 2016.
- "TED Talk - Kindness - Orly Wahba", Youtube/TED Conferences. Retrieved January 14, 2016.
- RABBI-UL-AWWAL (July 1998). "What is Kindness to Parents?". Islamic Voice. 12-07 (139).
- El-Sayed M. Amin. "Kindness to a Non-Muslim Neighbor: Tips for Interaction". Society. Islam Online. Archived from the original on 2005-08-28. Retrieved 2005-11-22.