"Man's best friend" is a common phrase used to describe domestic dogs, referring to their millennia-long history of close relations, loyalty, friendship, and companionship with humans. The first recorded use of a related phrase is by Frederick the Great of Prussia. It was likely popularized by its use in a poem by Ogden Nash and has since become a common colloquialism. Before the 19th century, breeds of dogs (other than lap dogs) were largely functional. They performed activities such as hunting, tracking, watching, protecting and guarding; and language describing the dog often reflected these roles. According to the Oxford English Dictionary, "In the oldest proverbs and phrases dogs are rarely depicted as faithful or as man’s best friend, but as vicious, ravening, or watchful." Beginning in the 18th century, multiplying in the 19th and flourishing in the 20th century, language and attitudes towards dogs began to shift. Possibly, this societal shift can be attributed to discovery of the rabies vaccine in 1869. Argos and Odysseus In Homer's Odyssey (c. 8th century BC), upon Odysseus' return, his beloved dog Argos is the only individual to recognize him. In Mahabharata This passage is from near the end of the Mahabharata, the Pandavas, having given up all their belongings and ties, made their final journey of pilgrimage to the Himalayas accompanied by a dog. Yudhishthira was the only one to reach the mountain peak in his mortal body, because he was unblemished by sin or untruth. On reaching the top, Indra asked him to abandon the dog before entering the Heaven. But Yudhishthira refused to do so, citing the dog's unflinching loyalty as a reason. It turned out that the dog was his god-father, Dharma. The story symbolized that dharma follows you until the end. Sources King Frederick of Prussia The statement Dog is man's best friend was first recorded as being made by Frederick, King of Prussia (1740–1786). Frederick referred to one of his Italian Greyhounds as his best friend. Poet C.S. van Winkle The earliest citation in the U.S. is traced to a poem by C.S. Winkle printed in The New-York Literary Journal, Volume 4, 1821: The faithful dog – why should I strive To speak his merits, while they live In every breast, and man's best friend Does often at his heels attend. Attorney George Graham Vest In 1870 Warrensburg, Missouri, George Graham Vest represented a farmer suing for damages