Mechanical refrigeration actually began in the 18th century, but was fully developed in its modern form in the 19th century by Carl von Linde, specifically for the brewing industry. Bilsch is right. Brewers always had temperature control. Deep cellars, tons of ice, and failing that, prohibitions against brewing when temperature could not be held low enough by these means. So brewing was historically a limited, seasonal activity, and mechanical refrigeration simply allowed us to brew year round. Thus temperature control has always been paramount in brewing. And if you are enjoying air conditioning or fresh food from your fridge, thank a brewer.