Book II.

Having finished my dissertation¹ concerning principles and elements and those things which chiefly appertain to them, I will turn my pen to discourse² of those things which are produced by them, and will take my beginning from the world, which contains and encompasseth all beings.

1 dissertation   

n.（博士学位）论文，学术演讲，专题论文

参考例句：

• He is currently writing a dissertation on the Somali civil war.他目前正在写一篇关于索马里内战的论文。
• He was involved in writing his doctoral dissertation.他在聚精会神地写他的博士论文。

2 discourse   

n.论文，演说；谈话；话语；vi.讲述，著述

参考例句：

• We'll discourse on the subject tonight.我们今晚要谈论这个问题。
• He fell into discourse with the customers who were drinking at the counter.他和站在柜台旁的酒客谈了起来。