Thoughts In Night Quiet, the old chestnut about homesickness by Tang poet Li Bai, is a simple classical Chinese poem I have known by heart most of my life.
It must be the best-known string of 20 words in Chinese, and children who learn the language are taught the poem even now, more than 1,000 years after it was written.
And yet, for the longest time, I didn't really, truly get the poem. I knew the words but I didn't hear the melancholy music of Li's lines. What I have realised only recently, after taking music classes and learning about scales and keys, is that I wasn't reciting the poem properly.
Like most students in Singapore, I learnt it in Mandarin. Although I am of Cantonese and Hakka descent, I was - and am - more familiar with the Mandarin version of Chinese poetry, if at all.
But reciting Thoughts In Night Quiet in Mandarin, I have found, is rather like playing a pensive minor-key piece in a joyful major key on a piano that has lost half its keyboard. It is, in other words, a disaster.
And teaching classical Chinese poems only in modern standard Mandarin is, I increasingly feel, a cruelty. Imagine telling young children all about the greatest songs in pop history. But you never ever play them the songs. You let them learn the lyrics - only the words, not the music. And for the rest of their lives, when they think of a Beatles or a Michael Jackson song, for instance, they will say the words aloud, but never be able to sing them.
The trouble with Mandarin, which enjoys official status in China and Singapore, is that it has lost the poetic register of ancient spoken Chinese.
As bilingual writer Li Lienfung explained in her book on poetry appreciation, Only A Sandpiper, Mandarin has long dropped the entering tone used by classical Chinese poets to express sorrow and rage.
A clipped sound that ends in a stop (-p, -t or -k), the tone can seem like a "deep, sad sigh" or a "shoe being sucked into a muddy puddle", she wrote.
River Awashed In Red, the song of anger by Yue Fei, the Song general who fought against the Manchurians, is an oft-cited example of a poem that drew its power from its rhyming entering tones.
Unfortunately, the Manchurians and Mongolians, two northern Asian tribes who eventually conquered China, also mangled the Chinese language, mispronouncing it so much that it lost the entering tone and developed into Mandarin, Li wrote.
The entering tone remains in older Chinese dialects, including Cantonese, Hakka, Hokkien and Hunanese. But the ascendancy of Mandarin has effectively ruined the music of Yue's poem for a broad swathe of the Chinese-speaking world, Li wrote.
I came across Li's chapter on the entering tone a couple of years ago, when I was browsing in a bookshop. As a rebellious child of Singapore's Speak Mandarin Campaign - although I speak enough Mandarin to be mistaken for a mainland Chinese, I resent how the local Chinese vernaculars, including Hokkien, Teochew and Cantonese, have been marginalised - I immediately relished her disdain for Mandarin.
But I wasn't well acquainted with Yue's poem, and didn't fully grasp the musical and emotional power of the entering tone. I just walked away with the impression that the entering tone was the A minor of Chinese poetry or something.
A few weeks ago, it all sank in though.
As I was reciting Thoughts In Night Quiet in Mandarin and Cantonese to a friend on a whim at lunchtime, I began listening to the poem more closely than I had in decades, with the benefit of my music lessons. It hit me then, what I had been missing out on for years.
Loosely speaking, whether in Cantonese or Mandarin, the poem has three rising lines (the first, second and fourth) and one falling line (the third). The rising lines end on the highest note - gwong (light), seung (frost) and heung (home) in Cantonese; guang, shuang and xiang in Mandarin. And the falling line ends on the lowest note - yuht (moon) in Cantonese; yue in Mandarin.
In Mandarin, which has four tones, the poem is rather flat, however. When you move from guang to shuang, or from yue to xiang, it's like walking on level or imperceptibly uneven ground. It's easy for you to end up rushing through and missing Li's words.
Cantonese, which has nine tones, including three entering tones (high, medium and low), is a sonic landscape with more pronounced peaks and valleys. In such a setting, you are more likely to pause and marvel at the song Li built. You may notice how yuht, a low entering tone which is used twice in the poem, makes a world of difference.
In the opening line (chong chin ming yuht gwong or "in front of the bed, the moonlight is bright"), yuht makes its solemn presence felt. A deep, narrow sound - deeper and narrower than yue - yuht is like a dark pit in the ground. It provides a stark contrast to gwong, such that gwong floats higher and feels brighter than seung in the second line and heung in the closing line.
The third line (geui tauh mong ming yuht, or "I raise my eyes to the moon") is the most dramatic one. Although the narrator is looking up, the poem is moving in the opposite direction tonally, descending from geui to ming and falling into a hole at yuht. Your voice drops here, into your throat, maybe your chest, and your heart might fall too.
The closing line rises tonally (dai tau si gu heung, or "I lower my head and long for home"), pulling you out of the depths of the poem. And something may come over you now - something like sorrow.
I felt it that afternoon as I recited the poem to my friend, and I was stunned. It was the first time I was hearing, and feeling, the tonal and emotional shift in Li's song.
My surprise soon became sadness though. This piece of melancholy has been preserved in this poem all this time, yet it has taken me three decades to taste it.