<blockquote>Antisthenes also, in his
book entitled The Natural Philosopher, says that while
there are many gods of popular belief, there is one
god in nature, so depriving divinity of all meaning
or substance. Very similarly Speusippus, following
his uncle Plato, and speaking of a certain force that
governs all things and is endowed with life, does his
best to root out the notion of deity from our minds altogether.
Source: Cicero in 28 Volumes. De Natura Deorum Academica. With English Translation by H. Rackham M.A. 1933. Internet Archive.
Source</blockquote>