And there will be a highway called the Way of Holiness. The unclean will not travel it—only those who walk in the Way—and fools will not stray onto it.Isaiah 35:8
In the time that these words were written, what was called a highway was what we would consider today a well-trodden trail. It was a definitive path that left no doubt as to the right way to go. Being on this trail brought with it a sense of confidence: all one had to do was to follow the trail to reach their destination.
The path of holiness is here called the Way. When one is on this path, one is separated from the rest of humanity that is choosing to follow its own desires.
Depending on which version of the Bible you may read, the last part of the verse can be viewed in a couple of meaningful ways. In some versions, like the Berean Study Bible quoted here, it gives the impressions that the fool will not accidentally stray onto it. This would imply that the Way is intentional; one chooses to be on it and does not fall upon it by whim or chance.
There are also versions that provide a different shade of meaning, such as “even a fool will not stray from it.” This gives the meaning that the Way is so clearly defined that even if one is foolish they have the ability to remain on the path.
In either view, the Way is something that is distinct from where the rest of the world travels. Being on the Way of holiness means one is traveling within a way of life that is intentionally set apart for God’s purposes, and this Way can keep even our foolish inclinations in check.