Next after Euclid's Elements the Elements of y^{e} Conic sections
are to be understood. And for this end you may read either the first part of
y^{e} Elementa Curvarum of John De Witt, or De la Hire's
late treatise of y^{e} conick sections, or Dr Barrow's epitome of
Apollonius.

For Algebra read first Barthin's introduction & then peruse such
Problems as you will find scattered up & down in y^{e}
Commentaries on Cartes's Geometry & other Alegraical writings of Francis
Schooten. I do not mean y^{t} you should read over all those
Commentaries, but only y^{e} solutions of such Problems as you will
here & there meet with. You may meet with De Witt's Elemenla
curvarum & Bartholin's introduction bound up together
w^{th} Carte's Geometry & Schooten's commentaries.

For Astronomy read first y^{e} short account of y^{e}
Copernican System in the end of Gassendus's Astronomy & then so much of
Mercator's Astronomy as concerns y^{e} same system & the new
discoveries made in the heavens by Telescopes in the Appendix.

These are sufficient for understanding my book: but if you can procure
Hugenius's Horologium oscillatorium, the perusal of that will
make you much more ready.

At y^{e} first perusal of my Book it's enough if you understand
y^{e} Propositions wth some of y^{e} Demonstrations
w^{ch} are easier then the rest. For when you understand
y^{e} easier they will afterwards give you light into y^{e}
harder. When you have read y^{e} first 60 pages, pass on to
y^{e} 3^{d} Book & when you see the design of that you may
turn back to such Propositions as you shall have a desire to know, or peruse
the whole in order if you think fit.