Angels speak practically, in the sense that they speak in signs. Because a sign is something that is clear. Whereas Jesus most often speaks in symbols. "The kingdom of God is like a seed." And symbols are not clear. At least not to the intellectual. A sign is like, "Turn left on Main Street. In the first house you’ll find a baby wrapped in swaddling clothes." A symbol is like, "To what shall I compare heaven? It is like a pinch of yeast in sixty pounds of flour."
Jesus himself is like a sign, or is a sign. Yet He speaks in symbols. Or more accurately because He speaks in symbols like a sign, He is a sign. And the only way to realize He is the sign is to understand His symbols. If you only follow the set of instructions that are clear, you never develop the ears to hear the instructions that you can’t see. And Jesus says the instructions you really need to be able to follow are the ones you can’t see. Not the ones you can.
A sign that you can’t read is a symbol. A symbol you can read is a sign.