Quote by Samuel Butler
Rare virtues are like rare plants or animals, things that have not been able to hold their own in the world. A virtue to be serviceable must, like gold, be alloyed with some commoner but more durable metal.
Summary
This quote suggests that rare virtues, just like rare plants or animals, are often unable to survive or thrive in society. In order for a virtue to be useful and effective, it needs to be mixed or combined with more common and enduring qualities, just as gold is alloyed with a more durable metal. Thus, this indicates that virtues should possess a balance of both rare and common characteristics to have a greater impact and longevity in the world.