How do I take captive every thought?

Each harsh thought we indulge in is a drag on the soul who is battling for his eternal life. How cowardly in anyone to cripple another either before or during his conscientious struggle to master his inner enemy. How dare we when we know we shall reap what we sow? How dare we throw that boomerang? No one who knows oppresses in any way the weak—I hate to appeal to your desire for self-preservation, but I can.