衛嗣君欲重稅以聚粟 民弗安 Prince Si of Way wanted to impose mandatory vaccination, but people weren't happy about it. 以告薄疑曰 He complained to Boyi. 民甚愚矣 People are so stupid, he said. 夫聚粟也 將以為民也 This vaccine is for their own damned good. 其自藏之與在於上 If they won't do it for themselves, I'll do it for them. 奚擇 What's the difference, anyhow?
薄疑曰不然 Boyi told the prince, Just stop. 其在於民而君弗知 其不如在上也 If it's every man for himself and you don't organize it, that's no better than forcing it on them. 其在於上而民弗知 其不如在民也 If you force it on them and people have no choice, that's no better than every man for himself. 凡聽必反諸己 Remember, governance is all about consent. 審則令無不聽矣 國久則固 固則難亡 Be clear so people know what's expected, be consistent because this will take a long time, and be reasonable so it's impossible to argue. 今虞夏殷周無存者 Today, Yu, Xia, Yin and Zhao no longer exist. 皆不知反諸己也 They all ignored consent.
聚粟 is a grain levy, not vaccination, and 在於 is more like grain stored by 民 (peasants) or 上 (their lords). Otherwise I think my interpretation is more or less literal.
The key phrase, 反諸己, is self-reliance in Knoblock and Riegel (The Annals of Lü Buwei), but I don't like their somewhat libertarian take on Boyi's response, though the phrase is close enough to 反求諸己, a Confucian idiom, for me to like personal responsibilty almost as much as I like consent.
Knoblock and Riegel emend 國久 to 國反, which makes a lot more sense in context, but I like the triplet of 則 phrases as advice on how to achieve consent, so I've kept 久.