Of all the seven deadly sins, envy is the last to be commodified. You can understand why unlike lust, anger or even sloth, it's not something to admit to. In his Allegory with Venus and Cupid, Bronzino depicted envy as an ugly green hag, clutching her head and howling impotently; now Instagram has allowed anyone online to gain access to images of the lifestyles of those richer, prettier and luckier than ourselves.