The poem "Ode to Autumn", written by John Keats in 1819, reflects the theme of growth and maturation in the following lines:
"(...) And full-grown lambs loud bleat from hilly bourn; hedge-crickets sing; and now with treble soft the red-breast whistles from a garden-croft; (...) "
In this poem the author wrote about the Autumn's cycle and the life's cycle, using the last prhases of the poem as the declining of the Autumn' season and the ineluctable end of the life. That is the main reason to write about full-grown lambs and the signing of the hedge-crickets, because when winter is coming the harvest is ended and animals have migrated, so the sounds of the animals mentioned in those lines are recovered only when spring comes.
The end of Autumn then, represent the idea of the declining in the life cycle.
