“I give myself very good advice, but I very seldom follow it.”

Letter I : Abelard To Philintus, as translated by John Hughes<!-- 1782 edition -->
Letters of Abelard and Heloise
Context: Sometimes I grieve for the house of the Paraclete, and wish to see it again. Ah, Philintus! does not the love of Heloise still burn in my heart? I have not yet triumphed over that happy passion. In the midst of my retirement I sigh, I weep, I pine, I speak the dear name of Heloise, pleased to hear the sound, I complain of the severity of Heaven. But, oh! let us not deceive ourselves: I have not made a right use of grace. I am thoroughly wretched. I have not yet torn from my heart deep roots which vice has planted in it. For if my conversion was sincere, how could I take a pleasure to relate my past follies? Could I not more easily comfort myself in my afflictions? Could I not turn to my advantage those words of God himself, If they have persecuted me, they will also persecute you; if the world hate you, ye know that it hated me also? Come Philintus, let us make a strong effort, turn our misfortunes to our advantage, make them meritorious, or at least wipe out our offences; let us receive, without murmuring, what comes from the hand of God, and let us not oppose our will to his. Adieu. I give you advice, which could I myself follow, I should be happy.

"The Beatings Must Continue" http://krugman.blogs.nytimes.com/2013/04/30/the-beatings-must-continue-2/, 30 April 2013
The Conscience of a Liberal blog

Trial of Dewhurst and others (1820), 1 St. Tr. (N. S.) 607.

Source: The Dangerous Summer (1985), Ch. 1

The Short Reign of Pippin IV (1957)

Dijkstra (1972) The Humble Programmer http://www.cs.utexas.edu/users/EWD/transcriptions/EWD03xx/EWD340.html (EWD340).
1970s
Context: After having programmed for some three years, I had a discussion with A. van Wijngaarden, who was then my boss at the Mathematical Center in Amsterdam, a discussion for which I shall remain grateful to him as long as I live. The point was that I was supposed to study theoretical physics at the University of Leiden simultaneously, and as I found the two activities harder and harder to combine, I had to make up my mind, either to stop programming and become a real, respectable theoretical physicist, or to carry my study of physics to a formal completion only, with a minimum of effort, and to become....., yes what? A programmer? But was that a respectable profession? For after all, what was programming? Where was the sound body of knowledge that could support it as an intellectually respectable discipline? I remember quite vividly how I envied my hardware colleagues, who, when asked about their professional competence, could at least point out that they knew everything about vacuum tubes, amplifiers and the rest, whereas I felt that, when faced with that question, I would stand empty-handed. Full of misgivings I knocked on van Wijngaarden’s office door, asking him whether I could “speak to him for a moment”; when I left his office a number of hours later, I was another person. For after having listened to my problems patiently, he agreed that up till that moment there was not much of a programming discipline, but then he went on to explain quietly that automatic computers were here to stay, that we were just at the beginning and could not I be one of the persons called to make programming a respectable discipline in the years to come? This was a turning point in my life and I completed my study of physics formally as quickly as I could. One moral of the above story is, of course, that we must be very careful when we give advice to younger people; sometimes they follow it!

Variant: Please give me some good advice in your next letter. I promise not to follow it.

Source: Ghost Story