“The price of the soul is faith. Faith is the lost drachma that the woman in the Gospel seeks diligently. We read that she lit a candle and swept her house. After finding it, she calls together her friends and neighbors, inviting them to rejoice with her because she has found the drachma she had lost.”
St. Ambrose in Ancient Christian Commentary on Scripture ed. Thomas Oden (Downers Grove, IL: IVP, 2003) 245.
“Or suppose a woman has ten silver coins and loses one. Does she not light a lamp, sweep the house and search carefully until she finds it? And when she finds it, she calls her friends and neighbors together and says, ‘Rejoice with me; I have found my lost coin.’ In the same way, I tell you, there is rejoicing in the presence of the angels of God over one sinner who repents.” Luke 15:8-10
“The damage to the soul is great if one has lost the faith. Light your lamp. Your lamp is the eye, that is, the interior eye of your soul. Light the lamp that feeds on the oil of the spirit and shines through your whole house. Search for the drachma, the redemption of your soul. If a person loses this, he is troubled, and if he finds it, he rejoices.”
St. Ambrose in Ancient Christian Commentary on Scripture, 245.