Thus we use our supposed "knowledge" of others to speak on their behalf, and condemn them for their words we ourselves put in their silent mouths.
The quote highlights the tendency of people to project their perceptions onto others, often judging them based on assumptions rather than true understanding. It suggests that individuals sometimes speak for others without permission, attributing thoughts and words to them that they may not actually hold. This can lead to unfair condemnation and misunderstanding.
In essence, the author underscores the danger of misinterpretation in social interactions, where one might mischaracterize another's beliefs or opinions. This reflects broader themes of communication and the complexities of human relationships, emphasizing the importance of listening and understanding before forming judgments about others.