Time’s Arrow

The sagittal axis¹ is an anatomical axis which extends forwards from the body. Points further along one’s axis are further ahead of them; the rear of the axis trails behind them.

In English, I think of the future as being ahead of me and the past behind. I can say that I am “looking forward” to something, or that “the worst is behind me”. Cher longs to “turn back time”. An exhibition might be a “retrospective” – the Latin adverb “retro” lends itself to hundreds of English words. In short, “before” and “after” are synonyms for “behind” and “ahead” in English. The flow of time is ➡️.

Chinese has a set of up/down particles: 上 shàng "up; above" / 下 xià "down; below". If events are an ordered list on a page, then 上次 shàngcì "last time" is upwards and 下次 xiàcì "next time" is downwards. This feels intuitive to me.

But Chinese has another set of particles: 前 qián "front; ahead" / 后/後 hòu "back; behind". This made a lot less sense to me when I first learned it.

Compared to the way I am used to thinking of time’s arrow (which extends outwards from my eyes and radiates ahead of me into the future), this is backwards. Consider 学前班 xué qián bān "preschool" which occurs 前 qián "before" school, an 派对之后 pài duì zhī hòu "afterparty" which occurs 后 hòu "after" a party, or the phrases 前天 qiántiān "day before yesterday" and 后天 hòutiān "day after tomorrow". Time’s arrow appears to flow backwards through the speaker.

But this also unlocks a lovely analogy: a speaker must walk blindly backwards towards the future. They can see the past, but the future lies forever out of sight.