There can be many answers to this question. Because everything is done by human efforts.
First, if you write in capital letters, you can write a word, such as "virtue", "love", "tranquility", "harmony" and "forbearance". You can also write two words, three words and four words, such as "submit to humiliation", "struggle", "learn to suffer losses", "cultivate humiliation and bear burdens", "bring things with kindness" and "kindness like water". You can also write five characters, six characters, seven characters and eight characters, such as "harmony is precious", "filial piety is a family heirloom", "quiet to cultivate one's morality", "indifferent to ambition, quiet to the distance" and so on.
Second, you can write couplets, such as "Nothing is difficult in the world, I'm afraid there is a will." Seven words, such as: "Don't be vulgar, it is difficult to learn from the ancients" and so on.
Third, you can write ancient poems. In five words, such as: "The snow presses the pine and cypress, and the pine and cypress are tall and straight. You have to know that it is loose and noble until it melts. " Seven words, such as: "Flowers on the mountain, flowers on the mountain, are not as good as flowers that smile loosely. One day, the frost came, and I saw that Song Qing didn't see flowers. "
Four: if you write in small print or small letters, you will write more content. Such as admonition book, hundred words inscription, love lotus theory, heart sutra and so on.
In short, the space is not large, and people can write within 300 words. Any more would be too small to look good.