If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.
Astronomy is a science. It teaches us the measurement and distances, and the nature and movements of the heavenly bodies. Navigation is astronomy applied to practice, and by the help of what astronomy tells the sailor, he is able to steer his vessel from one port to another, and ascertain exactly from his chart the position of his vessel. Is it not clear that every time out at sea the sailor unfolds his map and is enabled to mark on the chart the very spot where his ship is in the world's great space — every time he does that he has a fresh proof that astronomy is true. Every time he is able to bring his ship safely into port he has a fresh proof that science is true.
Parallel VersesKJV: If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.
WEB: If anyone desires to do his will, he will know about the teaching, whether it is from God, or if I am speaking from myself.