Final answer:
The original reason for adding brandy to wine was for preservation purposes, as brandy's high alcohol content acts as a natural preservative to prevent spoilage.
Step-by-step explanation:
Historically, the original reason for adding brandy to wine was for preservation purposes. In the past, wine would often spoil during long journeys or storage due to the presence of bacteria and yeast. Brandy, with its high alcohol content, acts as a natural preservative by inhibiting the growth of microorganisms that would otherwise cause spoilage. By adding brandy to wine, people were able to extend the shelf life of the wine and ensure its quality.