A wise teacher of mine once compared time to marbles. In the metaphor, you’re given a limited but unknown quantity of marbles. Along with the marbles, you have a collection of depositories that represent the activities and ends that constitute your life.

How you allocate the marbles is up to you. Suppose you wanted to, you could place all, or nearly all, your marbles in the jar representing ‘fun’ or ‘time spent with friends.’ You could also, if you liked, do your best to divide the marbles between categories, in an attempt to achieve a cohesive work-play balance.

The metaphor’s moral, at least as far as I interpreted it, is pretty straightforward: Time is limited, and it’s your responsibility to determine how you spend it. To take it one step further, choosing to engage or avoid certain activities prevents or enables participation in others.

Its simplicity notwithstanding, the metaphor is helpful — I think — because it allows us to visualize and concretize time and time’s evanescence — otherwise painfully abstract and intimidating.

At its start, college felt like Walmart; I thought it would go on forever. Three weeks into my senior year, how little time I have left as an undergraduate has hit me like a sack of tumbling hourglasses.

I’ve begun ticking off my last firsts. Last first day of fall semester. Last Welcome Back BBQ. Last first Thursday night of the year. Last first Saturday night back on State Street.

When did everything that was once so foreign become so familiar?

My biggest fear, I suppose, would be to see my time wind down without the confidence that I gave it my all. So while this column isn’t quite my swan song, senior year has gotten me thinking: Where am I going to place my marbles?

How do I want to spend my last months in Binghamton? How will I spend my last year as an undergraduate? Will I have made my mark, so to speak? What will my legacy be, if such a thing exists?

I want to spend time with my friends, that much is clear. We still have so many laughs to share and memories to make. By all accounts, after graduation, my friends are the ones I’ll miss the most, more than any course or assignment. But it’s also important that I do well this year. Leaving school and entering a dilapidated economy where my grades matter, I don’t want to sacrifice academic success.

And then there’s that whole employment thing. Yeah.

Or graduate school. Is that what I want to do next year? Should I have already taken something to make that happen? Some sort of exam with “AT” at the end of it? That’s what the kids are doing these days, right?

But I don’t want to go to graduate school just to avoid looking for a job. And what would I study? Sure, I could continue with English, I suppose. But is it my passion? I don’t know. I feel like if it were my passion, I would know. I mean, who else but me, right?

There’s also always philosophy graduate school, but boy, does that sound like a headache.

What is clear is that I need to spend some serious personal Mikey time in the weeks and months ahead sorting these questions out. In addition to enjoying my senior year, studying and working hard, I’ve got to devote some marbles to meditating on my next steps.

There is a certain comfort in being surrounded by all these uncertainties. For one thing, I know I’m not alone. I am going through this with peers and close friends at my side. We’re each entering an unknown.

And the unknowns are full of potential, I believe that. Maybe when what was once intimidating has grown comfortable it means it’s time to move on.

Soon enough the G word — graduation — will rear its ugly head. Hotel reservations will be made, caps and gowns will be ordered, yearbooks signed and, before I know it, I’ll be walking down the center aisle of the Events Center surrounded by a sea of green with my best friends at my side.

But I’m not ready for that just yet.