The above quote has obviously been attributed to Seneca The Younger (4 BC-65 AD). If you read many quotes by Seneca, you might question if he really said this. The wonder of the Intertunnel is that, by making so many original works available, it becomes possible, and is an interesting exercise, to track down the source quote. Sometimes, it is just not there. Then what? Consider this page from a Doubting Thomas at Wikiquote. Here are a few things did Seneca did say (with the original Latin and the source identified).
Non qui parum habet, sed qui plus cupit, pauper est.
- It is not the man who has too little, but the man who craves more, that is poor.
Nulli potest secura vita contingere qui de producenda nimis cogitat.
- No man can have a peaceful life who thinks too much about lengthening it.
Recede in te ipse quantum potes; cum his versare qui te meliorem facturi sunt, illos admitte quos tu potes facere meliores. Mutuo ista fiunt, et homines dum docent discunt.
- Withdraw into yourself, as far as you can. Associate with those who will make a better man of you. Welcome those whom you yourself can improve. The process is mutual; for men learn while they teach.
sciant quae optima sunt esse communia.
- The best ideas are common property.
Prope est a te deus, tecum est, intus est. Ita dico, Lucili: sacer intra nos spiritus sedet, malorum bonorumque nostrorum observator et custos...
- God is near you, with you, and in you. Thus I say, Lucilius: there sits a holy spirit within us, a watcher of our right and wrong doing, and a guardian...
sic cum inferiore vivas quemadmodum tecum superiorem velis vivere.
- Treat your inferiors as you would be treated by your betters.
errant consilia nostra, quia non habent quo derigantur; ignoranti quem portum petat nullus suus ventus est.
- Our plans miscarry because they have no aim. When a man does not know what harbour he is making for, no wind is the right wind.
Saepe aliud volumus, aliud optamus, et verum ne dis quidem dicimus.
- We often want one thing and pray for another, not telling the truth even to the gods.
Satius est supervacua scire quam nihil.
- It is better, of course, to know useless things than to know nothing.