From the fifteenth century the western world rose to global dominance in wealth, trade and military power. But as the West grew wealthier it did not grow healthier. The West’s populations were, from time to time, decimated by pandemic waves. Europeans devastated Amerindian populations by bringing them into contact with the common diseases of the Old World. Infections such as smallpox, measles, mumps, chickenpox and scarlet fever had a massive impact upon populations which had never experienced them before. The relationship between the health and wealth of nations was not lost on political and economic thought in the eighteenth century. The early modern political philosophy of mercantilism stressed the need to measure the strength of the state by assessing levels of health. Early modern exploration of probability and population had a powerful influence on the development of public health.