Leonardo’s remark suggests that mistakes often arise from insufficient thought. When people reach conclusions quickly, they may overlook relevant evidence, fail to consider alternatives or act on assumptions that have not been examined. Careful thinking can therefore reduce avoidable errors by creating space for comparison, reflection and correction.

The statement places responsibility on the quality of reasoning rather than on intelligence alone. Even a capable person can make poor judgements if they do not give a question enough attention. By contrast, deliberate thought allows uncertainties and contradictions to become more visible before a decision is made.

The quote can be applied to practical choices, study, investigation and debate. It does not imply that extensive reflection guarantees correctness, but it presents thoughtful consideration as an important safeguard against preventable mistakes and poorly supported conclusions.