才 cái is a pictograph of a sprout breaking through the ground. The oracle-bone and bronze forms show a young shoot pushing up past a line that marks the surface of the soil: the horizontal stroke is the ground, and the vertical stroke with its small turn is the first growth pressing through. The image is the very beginning of growth, the moment a thing first shows what it can become. Although 才 stands in the dictionary under the hand radical 扌 (shǒu), the glyph itself is a single integrated picture of the sprout rather than a hand plus a phonetic.

From this one image of nascent growth the character carries two intertwined threads:

1. Talent, ability, the gifted person. The promise in the sprout read as human potential: 人才 réncái (a talented person), 天才 tiāncái (genius), 才能 cáinéng (ability), 口才 kǒucái (eloquence). This is the noun 才, the raw capacity a person is born with or has cultivated.
2. The adverb: only then, not until, merely. Borrowed for sound, 才 became one of the busiest adverbs in Mandarin. It marks a fact as later, harder, or smaller than the listener might have assumed: 我现在才知道 "only now do I know," 八点才来 "did not come until eight," 才五块钱 "only five yuan."

The thread running through both senses is the bare minimum just emerging. The sprout is the least of what the plant will be, and the adverb 才 always points at a threshold barely crossed: the knowledge that arrives only just now, the guest who shows up only at last, the price that is only this small. Talent is the seed of much; the adverb is the just-so of a single moment.

The adverb 才 cái sits right before the verb and says that something happened later, more slowly, or only after some condition than the listener might expect. 他八点才来 means "he didn't come until eight" (later than wanted); 我现在才知道 means "only now do I know" (later than I should have). The same 才 marks a result that comes only once a condition is met: 你努力才能成功 "only by working hard can you succeed," 吃了药才好 "got better only after taking the medicine."

Two habits go with this 才. First, it usually takes no aspect marker 了 after the verb, because the focus is on the lateness or the condition, not on completion: 他昨天才到 "he only got here yesterday," not 才到了. Second, it pairs naturally with a leading clause of cause or condition, with the 才 in the second clause: 因为下雨，我们才取消了 "it was only because it rained that we canceled."

The sharpest way to feel the adverb is to set it against its mirror image, 就 jiù. See the comparison note below.

The same adverb 才 has a second, closely related job: before a number or amount it means "only, merely, no more than." Here the threshold is one of size rather than time, and 才 signals that the quantity is smaller than the listener might assume. 这本书才十块钱 "this book is only ten yuan," 他才十岁 "he's only ten," 我们才走了一半 "we've only walked half the way."

Both jobs of 才 share the same flavor: the speaker is pointing at a bare minimum and often nudging the listener's expectation. With time it is "no sooner than"; with quantity it is "no more than." In speech a light stress on 才 makes the smallness or the lateness vivid, and the sentence carries a faint note of surprise, complaint, or reassurance depending on context.

Picture a single sprout pushing up through the soil, the smallest first sign that something can grow. That sprout is the whole character. As a noun it is talent: the raw promise in a person waiting to unfold (人才, 天才, 才能). As an adverb it is the bare minimum just reached: the moment barely arrived, the amount barely there.

When 才 sits before a verb, hear "not until, only then": the thing came late or only after a struggle (八点才来, 努力才能成功). When it sits before a number, hear "only, merely": the amount is smaller than you thought (才五块, 才十岁). And remember its twin 就: where 才 says slow, late, hard, 就 says quick, early, easy. The little sprout always points at the least of a thing, just beginning to show.