Petrarch is credited with being the first "writer" of the Renaissance and his sonnets, formal short love poems, are seen widely as the basis for the evolution of this poetic form in England in later years. Petrarch, who wrote in the  is also sometimes referred to as the writer who started the Renaissance itself, because his emphasis upon classical myths and imagery are seen as the basis for the widespread rejuvenation of Classical motifs which inspired Renaissance writers and artists, as well as his poetry's focus upon beauty and romantic love, which became central themes for English poetry two hundred years later. Other themes, such as subjective experience, which relates the emotions of being in love to an individualistic set of feelings as opposed to a universal one, were first introduced in Petrarch's poems. Petrarch's use of natural settings and descriptions of natural beauty also influenced other Italian Renaissance writers, who wrote poems, plays and other works referred to as pastoral, a widespread convention in Renaissance literature, and this spread to writers in Portugal and Spain as well. This pastoral literature then inspired the wide body of English pastoral literature beginning in the mid 1500s, which celebrates and valorizes rural life and became the basis for many social and cultural assumptions about English culture.