There was once in Aragon a very pious King called Alphonsus. This King saw that most of the young Princes who dwelt in his Palace were very worldly and seldom, if ever, thought of prayer or of thanking God for the benefits they were daily receiving from Him.

One day he thought he would give them a lesson. He prepared a great banquet and invited them all to come to it. As soon as they were assembled he gave a sign to begin the meal. Not one of them thought of making the Sign of the Cross or of asking a blessing on their food before they began. In the midst of the enjoyment of the feast the door of the hall suddenly opened and a beggar came in. He was covered with rags and his whole appearance showed that he belonged to the lowest class of society.

Without saying one word, or even asking permission, he sat down amongst the nobles, not far from the King, and began to eat and drink as if he had as much right to be there as the others had. All the young nobles were full of indignation at such conduct and looked towards the King, wondering why he did not at once give orders that the intruder should be cast forth from the hall. But the King sat there in silence.

When the beggar had eaten and drunk as much as he could, he rose up, and without as much as looking at the King, or thanking him for the food he had received, turned towards the door and disappeared. As soon as he had gone out a murmur of disgust broke forth among the guests. "What impertinence!" they cried out; "a miserable man like him to dare to come in here, and to eat and drink at the King's table, as if all belonged to him, and to go away without saying even one word of thanks!" And for some time they continued to speak in the same strain of what had just occurred.

At length the King rose up and said: "My friends, you are wondering among yourselves why I permitted that poor man to remain in the room and you are indignant at his conduct. It was by my orders he came here. I wanted to give you a lesson. You speak of his impudence and his ingratitude and his rudeness. But you yourselves are as guilty as he, and even more so. Do you not daily receive from your Father in Heaven marks of His bounty and His love for you, and do you ever think of giving Him thanks? Let this be for you, then, a lesson. For the time to come, be grateful to Him, and never let a single day pass without thanking Him for the blessings He has bestowed upon you".

They bore the King's rebuke in silence, for they saw it was well deserved, and they profited by the lesson they received. 

The Catechism in Examples, Vol II, Pgs 46-48 by the Rev. D. Chisholm.