Two heads are better than one
Two people may be able to solve a problem that an individual cannot.
This proverb is first recorded in John Heywood's A dialogue conteinyng the nomber in effect of all the prouerbes in the Englishe tongue, 1546:
Some heades haue taken two headis better then one:
But ten heads without wit, I wene as good none.
'Head' here means 'mind', as opposed to heart or spirit. The notion of two being better than one, although not specifically two heads, was also expressed in the Bible; for example, this chapter from Ecclesiastes, 4:9, in in Miles Coverdale's Bible, 1535:
Therfore two are better then one, for they maye well enioye the profit of their laboure.
See also: the List of Proverbs.