In the early 17th century, the Netherlands was a country of prosperous, well-educated merchants and traders. This thriving middle class developed a taste for art and began to buy paintings just as they would shop for furniture and other household commodities. Painters found that scenes of everyday life had widespread appeal for the middle class, as did subjects that were just a little bawdy. The Dutch enjoyed sensual pleasures such as eating, drinking, and romancing, but they also sought reminders of the brevity of life and the need for moderation and temperance in one's own conduct. Art buyers preferred these moral teachings to be subtle and humorous rather than heavy-handed and stern, so painters often embedded visual metaphors in their paintings to encourage viewers to enjoy life but at the same time consider the consequences of overindulging their desires. It was also common for painters to use children to point out the foolish behavior of adults.
Cole TB. A Boy and a Girl With a Cat and an Eel. JAMA. 2009;302(7):721. doi:10.1001/jama.2009.1086