Gratitude
Overview
 
Gratitude, thankfulness, gratefulness, or appreciation is a feeling, emotion
Emotion
Emotion is a complex psychophysiological experience of an individual's state of mind as interacting with biochemical and environmental influences. In humans, emotion fundamentally involves "physiological arousal, expressive behaviors, and conscious experience." Emotion is associated with mood,...

 or attitude in acknowledgment of a benefit that one has received or will receive. The experience of gratitude has historically been a focus of several world religion
Religion
Religion is a collection of cultural systems, belief systems, and worldviews that establishes symbols that relate humanity to spirituality and, sometimes, to moral values. Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to...

s, and has been considered extensively by moral philosophers such as Adam Smith
Adam Smith
Adam Smith was a Scottish social philosopher and a pioneer of political economy. One of the key figures of the Scottish Enlightenment, Smith is the author of The Theory of Moral Sentiments and An Inquiry into the Nature and Causes of the Wealth of Nations...

. The systematic study of gratitude within psychology only began around the year 2000, possibly because psychology has traditionally been focused more on understanding distress rather than understanding positive emotions.
Quotations

We can set our deeds to the music of a grateful heart, and seek to round our lives into a hymn — the melody of which will be recognized by all who come in contact with us, and the power of which shall not be evanescent, like the voice of the singer, but perenninal, like the music of the spheres.

William Mackergo Taylor, reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 290.

Thankfulness is the tune of angels.

Edmund Spenser, reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 290.

Do not let the empty cup be your first teacher of the blessings you had when it was full. Do not let a hard place here and there in the bed destroy your rest. Seek, as a plain duty, to cultivate a buoyant, joyous sense of the crowded kindnesses of God in your daily life.

Alexander Maclaren, reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 290.

 
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