... only by way of desire, effort, and personal commitment can desirelessness be realised. Effort, as an expression of wholesome desire, leads along the path until with full realisation all desire will be abandoned.

"[i]n the body abide completing the body" to read: "in regard to your own body or the bodies of others, direct awareness to its (or their) impermanent nature evident in different aspects of the body, such as the process of breathing, or its postures and activities, or its anatomical constitution, or its elementary qualities, or its decay at death."

The term satipaṭṭhāna can be explained as a compound of sati, "mindfulness" or "awareness", and upaṭṭhāna, with the u of the latter term dropped by vowel elision. The Pāli term upaṭṭhāna literally means "placing near", and in the present context refers to a particular way of "being present" and "attending" to something with mindfulness. In the discourses, the corresponding verb upaṭṭhāhati often denotes various nuances of "being present", or else "attending". Understood in this way, "satipaṭṭhāna" means that sati "stands by", in the sense of being present; sati is "ready at hand", in the sense of attending to the current situation. Satipaṭṭhāna can then be translated as "presence of mindfulness" or as "attending with mindfulness".

The commentaries, however, derive satipaṭṭhāna from the word "foundation" or "cause" (paṭṭhāna). This seems unlikely, since in the discourses contained in the Pāli canon the corresponding verb paṭṭhāna never occurs together with sati. Moreover, the noun paṭṭhāna is not found at all in the early discourses, but comes into use only in the historically later Abhidhamma and the commentaries. In contrast, the discourses frequently relate sati to the verb upaṭṭhāhati indicating that "presence" (upaṭṭhāna) is the etymologically correct derivation. In fact, the equivalent Sanskrit term is smrtyupasthāna, which shows that upasthāna, or its Pāli equivalent upaṭṭhāna, is the correct choice for the compound.

In Chinese, it's translated as 念處 or 念住, which is quite opaque literally. Here're some annotation from 莊春江工作站：

「四念處(SA/MA/DA)；四意止(AA)」，南傳作「四念住」(cattāro satipaṭṭhānā)，菩提比丘長老英譯為「四個深切注意的建立」(four establishments of mindfulness)，並解說「satipaṭṭhāna」一詞，論師們有兩種解讀法，若解讀為「念+現起」(sati+upaṭṭhāna)，則為「念住；深切注意的建立」，若解讀為「念+出發點」(sati+paṭṭhāna)，則為「念處；深切注意的基礎」，前者強調「建立念的行為」，後者強調「應用念的所緣」，雖然論師多傾向後者，但前者確定是更原始的。按：四念處被稱為「自處父母境界」(SA.617)、「放牧處」(SA.1249)、「自洲自依」(SA.638)。

According to Analayo's reasoning, the correct Chinese translation should be 深切注意的建立.

According to the Ānāpānasati Sutta, it is possible to develop a variety of different aspects of satipaṭṭhāna contemplation with a single meditation object and in due course cover all four satipaṭṭhānas. This raises the question how far a single satipaṭṭhāna, or even a single meditation exercise, can be taken as a complete practice in its own right.

• Ānāpānasati Sutta: 安那般那念，雜阿含803經

Refrain:

In this way, / 如是,
in regard to the body he abides contemplating the body internally, / 比丘觀內身如身
or he abides contemplating the body externally, / 觀外身如身
or he abides contemplating the body both internally and externally. / [x]
He abides contemplating the nature of arising in the body, or he abides contemplating the nature of passing away in the body, or he abides contemplating the nature of both arising and passing away in the body. / [x]
Mindfulness that 'there is a body' is established in him / 立念在身
to the extent necessary for bare knowledge and continuous mindfulness. / 有知有見
And he abides independent, not clinging to anything in the world. / 有明有達
This is how in regard to the body he abides contemplating the body / 是謂：比丘觀身如身

I have problems understanding "abide contemplating" in English. For now, I mentally replace all "abides" to "keep", "stay", or "continue to".

What are the four? / 云何為四?
in regard to the body a monk abides contemplating the body, diligent, clearly knowing, and mindful, free from desires and discontent in regard to the world. / 觀身如身念處
in regard to feelings he abides contemplating ... / 觀覺如覺念處
in regard to the mind he abides contemplating ... / 觀心如心念處
in regard to dhammas he abides contemplating ... / 觀法如法念處

I can't find the part corresponding to "diligent, clearly knowing, and mindful, free from desires and discontent in regard to the world" in the ancient Chinese translation.

This is the direct path / 有一道
for the purification of beings, / 淨眾生
for the surmounting of sorrow and lamentation, / 度憂畏
for the disappearance of duhkka and discontent / 滅苦惱
[x] / 斷啼哭
for acquiring the true method, / 得正法 /
for the realization of Nibbānna, / [x]
namely, the four satipaṭṭhāna. / 謂：四念處。

Satipaṭṭhāna as the "direct path" to Nibbānna has received a detailed treatment in the Satipaṭṭhāna Sutta of the Majjhima Nikāya. Precisely the same discourse recurs as the Mahāsatipaṭṭhāna Sutta of the Dīgha Nikāya, the only difference being that this version offers a more extensive treatment of the four noble truths, the last of the satipaṭṭhāna contemplations. The topic of satipaṭṭhāna has moreover inspired several shorter discourses in the Saṃyutta Nikāya and the Aṅguttara Nikāya.

• Satipaṭṭhāna Sutta: 念處經，中部第 10 篇，對應《中阿含經》第 98 篇；
• Majjhima Nikāya: 中部，對應北傳《中阿含經》；
• Mahāsatipaṭṭhāna Sutta: 大念處經，長部第 22 篇;
• Dīgha Nikāya: 長部，對應北傳《長阿含經》；
• Saṃyutta Nikāya: 相應部, 對應北傳《雜阿含經》；
• Aṅguttara Nikāya: 增支部，對應北傳《增一阿含經》；

My plan is to read Analayo's translation along with the 念處經 from 中阿含經 and compare the differences.