As a native(-level†) English speaker (re-†)learning Chinese, one of the hardest things to wrap my brain around is how time is conveyed with the latter, since it’s quite conceptually different from the language of the former. I still don’t have a super firm grasp on all the nuances, but I want to share a mental model (read: metaphor XD) that I sometimes use to orient myself and that I hope will be helpful to other English↔︎Chinese‡ learners.

Ready? 走吧。

To start, the English language relies heavily on grammatical tense to convey any sense of time. In fact, since almost every sentence requires a predicate (i.e., a verb or verb phrase), and English predicates are always cast in some kind of temporal tense, one would be hardpressed to utter even the simplest English sentence without placing the action, even a hypothetical one, somewhere (somewhen? XD) in time. English speakers have to use the past, present, and future tenses (and their assorted subvariants) to locate events in the past, present, and future, respectively.

Chinese speakers, despite living in the same universe with the same laws of physics and time and all that, don’t. ‘^^ They use other means of expressing time. One of those is grammatical aspect.

What the hell is grammatical aspect?

(Yeah . . . ‘^^ They didn’t teach aspect in my grammar classes either. XD)

Tense tells you when in time something happens, implicitly or explicitly relative to a particular reference point. Did it (whatever “it” is) happen in the past? Is it going to happen in the future? Is it something that will have happened in the future’s past? Is it something that would have happened in the future relative to a particular point in the past (all of which is in the past now [“now” being the moment of utterance])? (Yes, there’s a tense for that: the future-perfect-in-past tense. You’re welcome. =P)

Aspect, on the other hand, tells you the temporal state of something (some action or event or whatever). Is it (again, whatever “it” is) still ongoing? Is it finished? Will it be finished relative to something that hasn’t happened yet? Is it something that happens habitually? In other words, aspect is about what’s going on in relation to the flow of time or with respect to a certain timeframe — that is, a certain situation whose boundaries are marked by a particular window of time or that has an endpoint marked by a specific event — much like a scene.

(Speaking of scene . . . )

Enter the extended metaphor.

Let’s say you’re meeting up with some friends somewhere, and they call or text you to ask, “Hey, where are you?” because they’re there at the meeting place and you’re not. How you answer reveals whether you think, structurally, like the English language or like the Chinese language.

If you answer with “I’m on Zhongxiao East Road, just passing SOGO”, then, well, you’re thinking like English. The where you’re giving is your grammatical tense, or your location. You’re saying, “I’m here at this point in time, relative to this other point in time”. Tense pinpoints where you are in the map of time itself. (Time is often conceived of as a line — hence, “timeline” —, but let’s 3D-ify it just for the sake of this spatial metaphor. If it helps, think of it as a very wide line — like, oh, I dunno, a street. =P) Then, from your location in time, your friends can infer other things — such as that you’re still en route —, just as, say, using the present (progressive) tense lets the listener/reader infer that the relevant action or event isn’t over yet — because it wasn’t located in the past.

If, instead, you answer their “Hey, where are you?” with “I’m almost there”, you’re thinking like Chinese. The where you’re giving is your grammatical tense, or your status in the situation. You’re saying, “I’m here in the process of getting there; my current state is ‘in progress’”. Aspect pinpoints where you are in the map of a scene, as it were. Are you at the beginning of the scene, where you haven’t even begun doing whatever it is you’re going to do; are you in the middle, where you’re in the midst of doing it; or are you at the end, where you’ve finished? (Or maybe it’s a montage scene where you’re doing something repeatedly over time [think: Rocky training], for, remember, aspect can also tell you whether an action or event is a regular one.) Then, from your location in scene, your friends can infer that you’re, presumably, somewhere between your home and where you all are meeting, just as the progressive aspect lets the listener/reader infer that the relevant action or event is still happening in the present — because it’s not yet been completed.

TL;DR:
If time were the GPS map you were using to get to your friends to meet up with them, tense would be the You Are Here dot representing you. Aspect would be the status update you give them: “On my way!” or “I’m here”. Being tense-centric, English cares much more about the GPS dot, the precise(-ish ‘^^) location in time. Being aspect-centric, Chinese cares more about the status update, the relative state of the action or event that’s happening.

(Now the real question is . . . what if you answer with “I’m on the bus”? XD)

†Yes, there’s a story behind this. ^.~

‡I am generalising from American English and Taiwanese Mandarin, the English and Chinese, respectively, I know best.