In Revelation, an angel tells John to eat a scroll, and as he eats it, it will be sweet in his mouth, and will make his stomach bitter. We like things that are sweet, we don't like things that are bitter, especially when it comes to what goes in our mouth. However, when it comes to things that touch our ears, we also probably would prefer to hear things that are sweet compared to things that are bitter. When it comes to God's Word, we need both. We need the bitter words of the Law, and the sweet words of the Gospel.