contribution to the science of optics. But the only strictly scientific
work Spinoza left behind (long considered to have been lost) was a short
treatise on the rainbow.

All Spinoza's intellectual energy went into service of his philosophy.
His earliest philosophical work (rediscovered (1862) in translated Dutch
manuscript) was a _Short Treatise on God, Man and His Well-Being_. It is
a fragmentary, uneven work, chiefly valuable for the insight it gives
into the workings and development of Spinoza's mind. The _Ethics_, in
the completed form in which we have it (no manuscript of it is extant)
has the incredible appearance of a system of philosophy sprung
full-grown from an unhesitating mind. Even a most cursory reading of the
_Short Treatise_ completely dispels this preposterous illusion. The
_Ethics_ was the product of prolonged and critical toil.

But just how prolonged it is difficult to say. For already as early as
1665 almost four-fifths of the _Ethics_ seems to have been written. We
learn as much from a letter Spinoza wrote to one of his friends
promising to send him the "third part" of his philosophy up to the
eightieth proposition. From the letter it is fairly clear that at that
time the _Ethics_ was divided into three, not five, parts. Also, in
letters written that same year to William Blyenbergh one finds expressed
some of the chief conclusions published five years later in the
_Tractatus Theologico-Politicus_. And Spinoza wrote, at this early
period, not conjecturally or speculatively, but as one writes who knows
the firm and tested grounds of his belief. Why the _Ethics_, in final
form, began to circulate privately only two or three years before
Spinoza's death, and why his work on _The Improvement of the
Understanding_ and his _Political Treatise_ were left unfinished, must
remain something of an insoluble philosophico-literary mystery.

The only book Spinoza published in his own lifetime above his own name
was his _Principles of Descartes' Philosophy Geometrically Demonstrated_
with an appendix of _Cogitata Metaphysica_ which he had dictated to a
youth (one "Caesarius") "to whom (he) did not wish to teach (his) own
opinions openly." Discretion, as he had already learned and later
formally stated and proved, was not inconsonant with rational valor. The
only other book Spinoza published in his lifetime--the _Tractatus
Theologico-Politicus_--bore on its title page Spinoza's initials only,
and the name of a