Ferdinand Bol, The Messenger of God Appearing to Joshua (1640-44)
When you actually get vision, it's pretty awesome. Paul the Apostle experienced an extreme example of this. He once got a vision from God so awesome that God allowed "a messenger of Satan" to afflict him ever after so that he wouldn't get full of himself. Vision can be that exhilarating. That might partly explain why it's so rare.
For this reason, it is crucial that everyone who seeks vision from God is focused like a laser on the glory of God. Vision is empowering, but ironically it can also distract from the Vision Giver. Those who are fired with zeal over the wonder of God's vision but get distracted from the Visionary God do more damage than a person with no vision at all. These people have much more energy than the average person, which makes their inadvertant misdirection that much more destructive. (Does this explain certain heresies and cults?) That's why God always starts the vision with a vision of himself.
Also for this reason, the vision doesn't just come from God but goes to God. He is both the beginning and end of true vision.
Joshua learned this lesson. Like other true visionaries of the first few books of the Bible, when Joshua met God as "the commander of Yahweh's army," he saw God (Josh. 5:14-15), then he saw what God was going to do (6:2), then he saw what he was supposed to do (6:3-5). The thing that God did—toppling the wall of Jericho in one instant with no siege equipment—was so far out there, so astonishingly impossible, that no one but God could get the credit. God gave Joshua that vision for God's own glory.
The next episode proves the point. Joshua led Israel to attack the small city of Ai, believing that it would fall without special assistance. To the contrary, without God helping the Israelites, the defenders of Ai routed them. Why? Because Israel did not adequately give the glory of the previous vision to God. One way this happened was through Joshua's failure to inquire of God how Ai was to be captured. But the bigger issue was that a guy named Achan took plunder from Jericho rather than leaving it for the Lord. The whole city, its inhabitants, and all it contained was to be devoted to God like a whole-burnt offering of the firstfruits of the conquest of Canaan—putting all the valuables in Yahweh's treasury, slaughtering everything that breathed, and torching the remainder. Achan's sin was attributed by God to all Israel as a failure to give him the glory he deserved. The glory he deserved, you see, was all of it. The barely noticeable fraction that Achan took for himself entirely compromised the whole. God's vision is for God's glory.
True, "the glory of God" is not specific enough to constitute vision in the concrete—that vision is about how God gets glory for himself, the specific way he intends masterfully to use frail and clumsy people as his instruments. Also truly, every person, church, or whatever should have as its ultimate objective the glory of God. So the glory of God is a given. But taking it as a given does not mean taking it for granted.
There is a grave temptation to fail at just this point. In fact, only those who have experienced the euphoria of truly grasping a vision and implementing it are allowed to reach the place where this temptation arises. It is they who have the greatest power to harm by failing at it. And so it is crucial on the front end, even before the vision is revealed perhaps, to be firmly convinced that God's vision is always, ever, only for God's glory.
When the only glory the visionary craves is to bask in the glory of the Vision Giver, then he or she is on the right track.