It advertises the Sappho fragment for sale by private treaty.

它通过私下方式宣传件萨福碎片。

A " private treaty sale" is a service whereby an auction house will broker a sale between vendor and buyer discreetly, outside the relatively public auction schedule.

" 私下" 是指拍卖行在相对公开的拍卖时间表之外，秘密地在卖方和买方之间进行中介销的服务。