The way of the wicked is as darkness: they know not at what they stumble.
– Proverbs 4:19
The way of wickedness is contrasted with the way of the just in the previous verse. The path of the just is a path of increasing light and the way of the wicked is a way of increasing darkness. It is a deepening darkness. It is a hazardous way that causes stumbling and falls. Thus it is to be avoided by preferably avoiding the entrance to it.