Man's sin consists in this that he so cleaves to bodily goods that he neglects what is good spiritually. It was therefore necessary for the Son of God to show this in the humanity he had taken, through all he did and suffered, so that men should repute temporal things, whether good or evil, as nothing, for otherwise, hindered by an exaggerated affection for them, they would be less devoted to spiritual things.
Christ therefore chose poor people for his parents, people nevertheless perfect in virtue, so that none of us should glory in the mere rank or wealth of our parents.
He led the life of a poor man, to teach us to set no store by wealth.
He lived the life of an ordinary man, without any rank, to wean men from an undue desire for honours.
Toil, thirst, hunger, the aches of the body, all these he endured, to encourage men, whom pleasures and delights attract, not to be deterred from virtue by the austerity a good life entails.
He went so far as to endure even death, lest the fear of death might at any time tempt man to abandon the truth. And lest any of us might dread to die even a shameful death for the truth, he chose to die by the most accursed death of all, by crucifixion.
--St. Thomas Aquinas
