Second Flag. A yellow flag. This stands for Caution. It means "Go slow, be careful." There are a great many things in life that may be harmless in themselves, but must be handled with care. Fire is a very useful thing. It prepares our food, and gives us comfortable heat for our homes, but we must handle fire with care, lest it break away from us and bring destruction to us all. So there are many acts we must watch, because if we do not heed the Yellow Flag of Caution it will bring great trouble into the world. We should always plant the yellow flag in the center of our amusements. Amusements, when they are pure and good, are right for us all. There is no harm in clean pleasures. God wants us to enjoy them, because we shall have pleasure forevermore in heaven, but here below evil pleasures are so mixed with the good that we must use the yellow flag of caution. Ask the children to name other things in which we must use caution, by reminding them that all doubtful things belong to this class. The yellow flag of caution should always fly over things we are not sure about. Third Flag. A blue flag. This flag is called the "working flag." When it is displayed on the track, it means the trackmen are working there. Often they are repairing the road, or working on a wreck. The blue flag, therefore, stands for work. God plants this flag in our path every hour. Boys and girls with bright eyes see this flag flying, and start and get busy. There is an office boy in Chicago of whom his employer is justly proud. He likes to tell how he came to take him on. Busy at his desk one morning, he looked up to see a little fellow waiting, cap in hand, to speak to him. He went on with his work and in about three minutes the boy spoke to him. "Excuse me, but I am in a hurry." "Oh, you are, well what are you in a hurry about?" "Got to be in a hurry. Left school day before yesterday to go to work, and haven't struck a job yet. If you don't want me, say so, and I'll look somewhere else. I can't waste any time. The only place where I stay long is where they pay me." "When can you come to work?" asked the surprised merchant. "I'm here now," said the boy, "and I'd have been to work five minutes ago, if you had said so." This lad saw the blue flag hanging from the window of the merchant's office, and he walked right in and reported for service at once. Over the gateway of the Lord's vineyard this blue flag is flying today. Jesus put it there, and on it is written in letters of gold, "Son, go work today in my vineyard." Let us walk in, and be as anxious to work for God as the lad was for the merchant. If we have an anxious heart and want to work with all our heart, we will see the blue flag flying everywhere. Lift up your eyes, and behold the world waving with blue flags. Fourth Flag. A green flag. This signifies "Go ahead, road clear." The church flies the green flag. Walk in. It is the gate to the road that has been made clear for you. Walk in. Walk in, the flag is green.