持而盈之不如其已 Once you get the hang of it, you quit when you're ahead. 揣而銳之不可長保 金玉滿堂莫之能守 You assume that when you've got it made, it won't take long to fall apart, and when gold and jewels deck public halls, that nothing can save your neck. 富貴而驕自遺其咎
When you're rich and powerful, pride brings shame upon itself. 功遂身退天之道 Step up, then step back down, that's how nature works.
This poem is a close parallel to a verse in Guanzi, 持而滿之乃其殆也 名滿於天下不若其已也 名進而身退天之道也. The Guanzi verse is part of a passage that seems to legitimize King Wu's usurpation, so I'm guessing that this poem was meant to be read in the same context, perhaps as advice on how to avoid the fate of the last Shang king.
Conventional translations of this poem are more literal than my interpretation, taking the subject of the first line as a cup, and of the second as a sword or knife. (Personally, I think the metaphor of the first line is more likely to be a Zhou tipping pot.) I prefer to read the 而 phrases as verb phrase conditionals, and to interpret 持 as bear in mind, 揣 as infer and the subject as 天之道. I also like the 金玉 line as a second then statement that also matches 揣.
The poem's Heshang Gong title is 運夷, revolving evenly.
天之道 as nature is a stretch, but interpreting 天 is always a stretch, so why not?