Short answers, pulled from the story.
Titus Lucretius Carus was a Roman poet and philosopher who lived approximately from 99 BC to the 15th of October, 55 BC. He is known almost exclusively through his single surviving work, the philosophical poem De rerum natura.
De rerum natura, usually translated as On the Nature of Things, is a poem of around 7,400 dactylic hexameters divided into six untitled books. It explains the philosophy of Epicureanism, covering atomism, the nature of the mind and soul, sensation, the development of the world, and celestial and terrestrial phenomena, all without reference to divine intervention.
De rerum natura was nearly lost during the Middle Ages but was rediscovered in 1417 by the Florentine humanist Poggio Bracciolini in a monastery in Germany. Bracciolini had the manuscript copied, which re-introduced the poem to European intellectual life.
Lucretius is credited with originating the concept of the three-age system by describing successive human use of wood and stone, then copper and bronze, then iron in De rerum natura. His theory lay dormant for many centuries before C. J. Thomsen formalized it from 1834.
In a letter to his brother Quintus in February 54 BC, Cicero wrote that the poems of Lucretius "exhibit many flashes of genius, and yet show great mastership." Cicero's edition of the poem is also mentioned in Jerome's account of Lucretius's life.
Prior to Charles Darwin's 1859 publication of On the Origin of Species, Lucretius's natural philosophy was recognized as one of the foremost non-teleological and mechanistic accounts of how life developed. He argued that organisms best adapted to their environment have the greatest chance of surviving, though he did not believe new species arose from previously existing ones.