William Penn (1644-1718), founder of Pennsylvania, opens his book Some Fruits of Solitude with the following line:
Reader,—This Enchiridion, I present thee with, is the Fruit of Solitude: A School few care to learn in, tho’ None instruct better. Some Parts of it are the Result of serious Reflection: Others the Flashings of Lucid Intervals: Writ for private Satisfaction, and now publish’d for an Help to Human conduct.
Just as Marcus Aurelius wrote his own journal in his free time to solace himself, so Penn has done the same, recording his own wisdom, publishing it in hopes of inspiring others through his wisdom; and just like the former, his advice is for everyone and ought to be looked at.
57. Love Labor: For if thou dost not want it for Food, thou mayest for Physick [physique]. It is wholesom [sic.] for thy Body, and good for thy Mind. It prevents the Fruits of Idleness, which many times comes of nothing to do, and leads too many to do what is worse than nothing.
Qualities of a Friend
111. A true Friend unbosoms freely, advises justly, assists readily, adventures boldly, takes all patiently, defends courageously, and continues a Friend unchangeably.
Rules of Conversation
131. If thou thinkest twice, before thou speakest once, thou wilt speak twice the better for it.
237. Do good with what thou hast, or it will do thee no good.
239. We are apt to call things by wrong Names. We will have Prosperity to be Happiness, and Adversity to be Misery; though that is the School of Wisdom, and oftentimes the way to Eternal Happiness.
241. Have but little to do, and do it thy self [sic.]: And do to others as thou wouldest have them do to thee: So, thou canst not fail of Temporal Felicity.
249. Too few know when they have Enough; and fewer know how to employ it.
303. Opportunities should never be lost, because they can hardly be regained.
308. Neither despise, nor oppose, what thou dost not understand.
For further reading: Some Fruits of Solitude by William Penn (1968)