With great power comes great responsibility, words that Griffin cannot live by in this case.
Having successfully discovered the secret to invisibility, using light refraction, Griffin is initially delighted by his discovery which he imagines is going to give him the key to power and access in the world.
Griffin finds himself hounded and attacked by everyone who senses his presence. Obtaining food, finding shelter, even walking down a crowded street become nightmarishly difficult tasks. This can be made even harder by rain, snow or even fog providing outlines and footsteps.
The difficulties of surviving, of being constantly naked, combined with the strain caused by years of research at the expense of all else, turns Griffin's mind into a very dark place indeed. From initially being something to welcome invisibility ultimately becomes a means by which vengence can be taken through his Reign of Terror.