Redeeming the time, because the days are evil | Buying up for yourselves the opportunity
The idea being that of a merchant who, knowing the value of an article and the good use to which he can put it, buys it up. The opportunity is the opportunity of spreading the light and acting according to it; and the reason assigned, "because the days are evil," indicates that, owing to the prevalence of evil, there is much need for the light over which the Christian has control. It may be hinted likewise that the prevalence of evil is apt to cool the love and diminish the zeal of the Christian; hence the need for special eagerness of spirit in the matter - he must passionately watch for his opportunity.
This Latin phrase, which literally means "pluck the day," was used by the Roman poet Horace to express the idea that we should enjoy life while we can. His full injunction, "carpe diem quam minimum credula postero,” can be translated as “pluck the day, trusting as little as possible in the next one,” but carpe diem alone has come to be used as shorthand for this entire idea, which is more widely known as "seize the day."
Gather ye rosebuds while ye may,
Old time is still a-flying;
And this same flower that smiles today
Tomorrow will be dying.
While the sentiment has long been expressed in English, the phrase carpe diem didn't begin appearing in print in English until the early 19th century. Two centuries later, the phrase is found on mugs and T-shirts and in the names of various enterprises and organizations.