In times of old, ancient fortresses had exceptionally thick, high, impenetrable walls intended to keep intruders out. When we choose to fill our hearts and minds with the wisdom of God's Word, it builds a strong fortress of truth, that stops the lies and fearful thoughts of the enemy from hitting their mark in our minds, and rooting themselves in our lives. The light of God's Word shines strong on every incoming thought. If the thought is contrary to the truth and nature of God's Word, we can immediately take it captive and cast it out, before it causes any damage in our lives. Making the Lord our fortress is choosing to make His Word our final authority. We don't have to tremble or be in fear, the Word becomes our safe haven, protecting us from the attacks of the enemy.