Alfred, Lord Tennyson

Alfred Tennyson, 1st Baron Tennyson, FRS (6 August 1809 – 6 October 1892) was Poet Laureate of the United Kingdom in the Victorian era. He remains one of the most popular poets in the English language.
Tennyson was excellent at writing short lyrics like "In the valley of Cauteretz", "Break, break, break", "The Charge of the Light Brigade", "Tears, idle tears" and "Crossing the Bar". Much of his verse like The Lotus Eaters was based on classical mythological themes. Tennyson also wrote some notable blank verse including "Idylls of the King", "Ulysses", and "Tithonus". During his career, Tennyson attempted drama, but his plays were not very successful.
Red in tooth and claw.
"In Memoriam A.H.H." was a poem by Tennyson, written in memory of his best friend Arthur Hallam. Hallam was a fellow poet and classmate at Trinity College, Cambridge. He had been engaged to Tennyson's sister, but died from a cerebral hemorrhage before they could get married.
The poem was published after Tennyson had read a pro-evolution book by Robert Chambers. The fundamentalist idea of Biblical inerrancy was in conflict with science. Tennyson expressed the difficulties evolution raised for faith in "the truths that never can be proved".
The poem is too long to quote in full, but this shows how he was thinking of the living world:
The much-quoted phrase comes soon after, in section 56. It refers to humanity: 
The phrase "Nature, red in tooth and claw" was taken up as a metaphor for life in general, even before Darwin's "Origin of species" was published.
"Tis better to have loved and lost"....
The poem has another, perhaps even better-known stanza: