Full Idea
Although people can be made worse off by all other gifts, correct reasoning alone can only be for the good.
Gist of Idea
All other human gifts can harm us, but not correct reasoning
Source
Gottfried Leibniz (Preface to Universal Characteristic [1679])
Book Reference
Leibniz,Gottfried: 'Philosophical Essays', ed/tr. Arlew,R /Garber,D [Hackett 1989], p.8
A Reaction
How about a kind heart? Not everyone would agree with the remark, but philosophers should.