Full Idea
The highest task which nature has set mankind is to establish a society in which freedom under external laws would be combined to the greatest possible extent with irresistible force, in other words of establishing a perfectly just constitution.
Gist of Idea
Our aim is a constitution which combines maximum freedom with strong restraint
Source
Immanuel Kant (Idea for a Universal History [1784], 5th)
Book Reference
Kant,Immanuel: 'Political Writings', ed/tr. Reiss,Hans [CUP 1996], p.45
A Reaction
The 'force' is to restrict the harms that may result from individual freedom. This seems to equate justice with liberal freedom. Force can prevent direct harm to others, but what to do about indirect harm? Many lack freedom, but whose fault is it?