单丝不成线，独树不成林单丝不成线，孤树不成林；独木不成林dān sī bù chéng xiàn,dú shù bù chéng lín

a single thread does not make a cord nor a single tree a forest; one strand of silk is not a thread,one tree is not a wood; one person alone cannot ac complish much
❍ 湘云因说他：“你放心闹罢，先还‘～’，如今有了个对子了。……”(《红楼梦》719)“Now you can be as naughty as you like，”she teased. “Before this it was a case of ‘A single thread can’t make a cord nor a single tree a forest.’ But now that there are two of you，…”/朱老巩死了，他失去了一条膀臂，单丝不成线，孤树不成林，只怕冯家对他不利。(梁斌《红旗谱》26) Zhu Laogong’s death had robbed him of a staunch friend and ally. One strand of silk is not a thread,one tree is not a wood. And now Feng meant mischief.