But for God’s permission and allowance [for occasional spiritual depression] there is a twofold reason. First, that being for a short time forsaken by the Lord, and observing with all humility the weakness of our own heart, we may not be puffed up on account of the previous purity of heart granted to us by His visitation; and that by proving that when we are forsaken by Him we cannot possibly recover our former state of purity and delight by any groanings and efforts of our own, we may also learn that our previous gladness of heart resulted not from our own earnestness but from His gift, and that for the present time it must be sought once more from His grace and enlightenment.
St. John Cassian, c. 360 – 433.
Check out this hilarious comparison of Crissmas and Exmas by C.S. Lewis.
every citizen is obliged to send to each of his friends and relations a square piece of hard paper stamped with a picture, which in their speech is called an Exmas-card . But the pictures represent birds sitting on branches, or trees with a dark green prickly leaf, or else men in such garments as the Niatirbians believe that their ancestors wore two hundred years ago riding in coaches such as their ancestors used, or houses with snow on their roofs. And the Niatirbians are unwilling to say what these pictures have to do with the festival, guarding (as I suppose) some sacred mystery. And because all men must send these cards the market-place is filled with the crowd of those buying them, so that there is great labour and weariness.
Food for thought.