Gregory the Great — as excerpted in the Catena Aurea on Matthew 20:1-16

“(ubi sup.) There be very many come to the faith, yet but few arrive at the heavenly kingdom; many follow God in words, but shun Him in their lives. Whereof spring two things to be thought upon. The first, that none should presume ought concerning himself; for though he be called to the faith, he knows not whether he shall be chosen to the kingdom. Secondly, that none should despair of his neighbour, even though he see him lying in vices; because he knows not the riches of the Divine mercy. Or otherwise. The morning is our childhood; the third hour may be understood as our youth, the sun as it were mounting to his height is the advance of the heat of age; the sixth hour is manhood, when the sun is steady in his meridian height, representing as it were the maturity of strength; by the ninth is understood old age, in which the sun descends from his vertical height, as our age falls away from the fervour of youth; the eleventh hour is that age which is called decrepit, and doting.”