Mark 8:8

After the multitude had eaten and were filled, they did not take the remains; but these the disciples collected, as in the former miracle of the multiplication of the loaves. By this circumstance we are taught to be content with what is sufficient, and to seek no unnecessary supplies. We may likewise learn from this stupendous miracle the providence of God and his goodness, who sends us not away fasting, but wishes all to be nourished and enriched with his grace. (Theophylactus) --- Thus does our Lord verify in his works what he has promised in his instructions; that if we will seek in the first instance the kingdom of God and his justice, that all necessary things shall be added unto us. By the gathering up of the fragments that remained, he not only made the miracle more striking to the multitude and to the apostles, but has also left us a practical lesson, how, in the midst of plenty, which proceeds from the munificence of heaven, we must suffer no waste. (Haydock)