Ambrose of Milan
Catena Aurea · Lukasevangelium 12
And I say unto you my friends, Be not afraid of them that kill the body, and after that have no more that they can do. But I will forewarn you whom ye shall fear: Fear him, which after he hath killed hath power to cast into hell; yea, I say unto you, Fear him. Are not five sparrows sold for two farthings, and not one of them is forgotten before God? But even the very hairs of your head are all numbered. Fear not therefore: ye are of more value than many sparrows.
Or else; A good sparrow is one which nature has furnished with the power of flying; for nature has given us the grace of flying, pleasure has taken it away, which loads with meats the soul of the wicked, and moulds it towards the nature of a fleshly mass. The five senses of the body then, if they seek the food of earthly alloy, cannot fly back to the fruits of higher actions. A bad sparrow therefore is one which has lost its habit of flying through the fault of earthly grovelling; such are those sparrows which are sold for two farthings, namely, at the price of worldly luxury. For the enemy sets up his, as it were, captive slaves, at the very lowest price. But the Lord, being the fit judge of His own work, has redeemed at a great price us, His noble servants, whom He hath made in His own image.