Cast ye the unprofitable servant into [the] outer darkness (Matthew 8:12). The parable merges into the real. The 'matter represented bursts through the veil under which it was delivered, and stands forth plainly and awfully.
The command is issued to the ministers of the Lord's vengeance, whether earthly or angelic. The slave was truly unprofitable, as he advanced neither his master's interests nor his own, which were bound up with the other.
While the faithful servants enter into the joy of the Lord, he is rejected from his presence, expelled from the kingdom of heaven, banished we know not whither. And why? Not for great ill doing, sacrilege, crime, offence against the common laws of God and man; but for neglect, idleness, omission of duty.
This is a very fearful thought. Men endeavour to screen themselves from blame by minimizing their talents, ability, opportunities; this parable unveils the flimsiness of this pretence, shows that all have responsibilities, and are answerable for the use they make of the graces and faculties, be they never so small, which they possess.
Spiritual indolence is as serious a sin as active wickedness, and meets with similar punishment, Our Lord's account of the last judgment terribly confirms this truth (Matthew 25:42-45). There shall be [the] weeping and [the] gnashing of teeth (Matthew 24:51).
"There," viz. in the outer darkness. The remembrance of lost opportunities, wasted graces, bartered privileges, will fill the mind of the banished with terrible remorse, and make existence a very hell; and what more shall be added?
Some of the Fathers have recorded a gnomic saying derived from this parable, if not an utterance of our Lord himself, "Be ye approved bankers."