It’s the famous phrase inscribed over the Temple at Delphi, where people seeking to know the future came to meet the Oracle. “Know thyself.”

Philosophers spend their whole working lives effectively doing that. For the rest of us, it tends to be more of a hit-and-miss affair: we’ll do it when we have to.

These days, I’d add “Know your times” as well. The two go together, if you’re looking to judge what to do with your own future.

You can, for instance, find your passion (that’s a common piece of advice) and turn it into a full Zentrepreneurial opportunity (both work and life as one). But that doesn’t mean the times allow for it to succeed, no matter how hard you work at it.

Likewise, all the hundreds of millions that can flow from being the CEO of a Fortune 100 company do nothing for you if it’s the wrong place for you to be.

Most of us get wrapped up on a path early, perhaps before we’ve had a good chance to sort out who we are, what we do best, and how it fits into our times.

Expecting employers to sort that out for us is a mug’s game. Unfortunately, many do. Some do it by changing jobs repeatedly. Others do it by waiting patiently to be told what to do next.

Neither strategy works in our time, most of the time.

But that doesn’t mean you should rush out and do your own enterprise, either. “Know thyself”, remember? Not everyone is temperamentally suited to dancing on a high-wire without a net day after day. Not everyone’s family is capable of holding back their worries and providing support for a fledgling’s flight.

If you’ve got it, great … and yet, still, you might be as much a fish out of water in that role as a Grade 3 teacher would be suddenly asked to lead Apple Corporation. Can you do it if you have to? Perhaps. Should you? Ah, a better question!

In our time, more and more of us will need to carve out our own paths for at least some of our working life. The days of William Whyte’s Organization Man are long past. Global competition, acquisitions and changing marketplaces have ripped up the old certainties. Governments so deeply in debt that “austerity” is the only course are tearing away at the public sector’s stability. These are facts of our time.

The other part of “know thyself” and “know thy time” is to recognize that as you change, who you are changes too.

This is what the philosopher Thomas Langan called our natural faith — those unstated assumptions about how it is. Changes in our lives change our natural faith. (It’ll even show up on the psychological tests, like Myers-Briggs: take one while you’re a cubicle drone, then take it again a decade later while you’re a consultant, or an entrepreneur, and see how your profile has shifted.)

So it’s worth revisiting from time to time, and never more so than when you’re about to think about career changes (or have had them thrust upon you).