"Drink heartily, make merry with wine" means having a good mood, talking from the heart and enjoying drinking. It expresses a carefree state, which makes people feel very happy and comfortable. It can enhance feelings and relax. It is a very pleasant social way, and the two sentences are well connected.
"Drink to your heart's content" means to drink to your heart's content, feel happy and feel very happy. "Drink to your heart's content" means to drink to your heart's content, freely and freely. "Happy" means "Isn't it very pleasant", which means that something makes people feel very happy and happy. This sentence is often used to describe the joy and carefree when people drink together.