Ancient science was mostly based on observation and theory. They did some experiments (e.g. Strato and Archimedes) and attempted to describe nature with mathematics (e.g. Plato, Callipus and Ptolemy). However, it was first in the seventeenth century that experiment began to be an integral part of the study and understanding of nature, and it was first then that one also began to be able to describe nature accurately enough to formulate mathematical laws (e.g. Kepler, Boyle and Newton).