For working class people, the purpose of a dowry was to make sure the new husband had the resources to take care of the daughter so they didn't starve. It was literally, "here's a couple of goats to get you through the winter. After that you're on your own."

For wealthier people, a dowry was effectively paying the husband for access to his position in society. In both cases, it was about making sure the woman would be able to live in the style she was accustomed to.