The following is the opening of Letter V of the Letters Concerning the Love of God, a correspondence between Astell and Norris on the "Seraphick" subject of love. This selection doesn't get into very much of the heavier thought of the letters, but I have picked this one out for several reasons.
1. It contains Astell's description of her philosophical work, "I have courted Truth with a kind of Romantick Passion," which is one of my favorite summations of philosophy ever.
2. It gives something of the situation of women in the late 17th century, as seen from the perspective of a largely self-taught woman of considerable brilliance.
3. It also conveys Astell's sense of the purpose of philosophical thought, and its role with regard to the development of the human person.
This letter was written December 12, 1693. After this opening, she goes on to clarify their common ground the question they had previously been discussing (whether God is the cause of pain), and then, because she has been asked by Norris to do so, to present her views on the nature and effects of love of God. They spend most of the rest of the correspondence on this topic. It becomes a rather substantive philosophical discussion that grows out of a philosophical agreement. It is not, as most significant philosophical correspondences are, an epistolary debate; rather, it is an epistolary collaboration in which they both assist each other in clarifying various issues related to their topic of discussion.
So candid and condescending a Treatment of a Stranger, a Woman, and so inconsiderable an one as my self, shews you to be as much above the Generality of the World in your Practice, as you are in your Theory and Speculation. Hitherto I have courted Truth with a kind of Romantick Passion, in spite of all Difficulties and Discouragements : for knowledge is thought so unnecessary an Accomplishment for a Woman, that few will give themselves the Trouble to assits us in the Attainment of it. Not considering that the improvement of one single Soul is an Employment more worthy of a wise Man, than most of those things to which Custom appropriates the Name of Business and Affairs. But now, since you have so generously put into my Hand an Opportunity of obtaining what I so greedily long after, that I may make the best Improvement of so great an Advantage, I give up my self entirely to your Conduct, so far as is consistent with a rational not blind Obedience, bring a free and unprejudiced Mind to receive from your Hand such Gravings and Impressions as shall seem most convenient, and though I can't engage for a prompt and comprehensive Genius, yet I will for a docible Temper.
The Esteem I have for those necessary and useful Rules you have already presribed, shall appear by my strict Observation of them : For indeed the Span of Life is too short to be trifled away in unconcerning and unprofitable Matters; and that Soul who has any Sense of a better Life, can't chuse but desire that every minute of her Time may be employed in the regulating of her Will with the most critical Exactness, and the extending her Understanding to its utmost stretch, that so she may obtain the most enlarg'd Knowledge and ample Fruition of GOD her only Good, that her Nature is capable of.