It is by a thorough knowledge of the whole subject that [people] are enabled to judge correctly of the past and to give a proper direction to the future.
![It is by a thorough knowledge of the whole subject that [people] are enabled to judge correctly of the past and to give a proper direction to the future.](http://cdn.quoteddaily.com/images/john-quincy-adams/it-is-by-a-thorough-knowledge-of-the-whole-subject-that-people-are-enabled-to-judge-correctly-of-the-past.jpg)
It is by a thorough knowledge of the whole subject that [people] are enabled to judge correctly of the past and to give a proper direction to the future.