Fortifications are militaryconstructions designed for defensivewarfare. They have been used for many thousands of years, in a variety of increasingly complex designs. The practice of improving an area's defense is also known as "fortification". Many military installations are known as forts, although they are not always "fortified".
... Erläuterungen des Hegelschen Systems (1840)
Vorlesungen über Schelling (1842)
System der Wissenschaft (1850)
Meine Reform der Hegelschen Philosophie ...