Happy Stoic Week! One of this week’s morning meditation passages, from Marcus Aurelius, reads in part:
There is nowhere that a person can find a more peaceful and trouble-free retreat than in his own mind, especially if he has within himself the kind of thoughts that let him dip into them and so at once gain complete ease of mind.
The title of Pierre Hadot’s book on Marcus Aurelius, Inner Citadel, reflects this notion of Marcus Aurelius’ that one’s own mind can–if fortified–be an ideal source of strength and tranquility. A citadel, traditionally located in the heart of a city, is meant to withstand attack from outside forces. Despite humans’ innate capacity for rationality, the mind itself is subject to invasion by barbarous thoughts, desires, and emotions, and must be fortified like a citadel with the help of philosophy.
Your three components: body, breath, mind. Two are yours in trust; to the third alone you have clear title. . . . If you can cut free of impressions that cling to the mind, free of the future and the past–can make yourself, as Empedocles says, “a sphere rejoicing in its perfect stillness,” and concentrate on living what can be lived (which means the present) . . . then you can spend the time you have left in tranquility. And in kindness. And at peace with the spirit within you. Med. 12.3
Marcus was likely using the Greek word “phantasiai” for impressions in the passage above, as he did throughout the Meditations. According to the entry on “Stoic philosophy of mind” in Internet Encyclopedia of Philosophy, which translates phantasiai as presentations, “The most basic power of the hêgemonikon is the ability to form presentations [phantasiai]. Other psychological states and activities such as mental assent, cognition, impulse, and knowledge are all either extensions or responses to presentations.” (Boldface emphasis is mine. Hegemonikon is often translated as “central commanding faculty.”) Keeping in mind the Greek term has helped me keep potentially “fantastic” impressions in perspective.
I read the IEP’s characterization of our mind’s formation of impressions as a “basic power” to imply a sort of kneejerk quality–certainly qualifying as a human reaction, but not necessarily sophisticated or well-reasoned. According to the Stanford Encyclopedia of Philosophy,
Plato’s Protagoras, which greatly influenced the Stoics, can help us here. This text contrasts the power of phantasia (often translated ‘appearance’) with an art of measurement, the former often going wrong because comparative or perspectival (A looks tall because she’s beside the very short B; B looks taller than A because she’s closer to me), and standing in need of correction by an unchanging standard (a meter ruler, for example) (356b-57a). That Marcus may find the same defects of isolation and perspective in impressions is suggested indirectly by the corrections he prescribes: inspect your impressions (ii.7, iii.6, v.22, viii.13, viii.26); test them by ‘physicizing, ethicizing, dialecticizing’ (viii.13), that is to say, by seeing how they fare when tested against your physical, ethical, and dialectical understanding—all of which are informed by a picture of the whole.
It then quotes Meditations 12.18, but I prefer the Gregory Hays translation:
At all times, look at the thing itself–the thing behind the appearance–and unpack it by analysis:
- And the length of time it exists.
Hays’ rendering, “the thing behind the appearance,” resonates with me. It reminds me not to conflate the appearance with the truth, and it is easy to repeat to myself as a mantra.
This Stanford Encyclopedia entry notes Marcus’ tendency to tell himself to “erase” his impressions, but what does that mean? It cites Hadot, who believes that “by ‘erase impressions’ Marcus means ‘assent only to objective and physical descriptions of externals’. What Marcus is telling himself to erase, Hadot says, is value-judgments about everything external to his character.” 
So, to go back to yesterday’s passage from the Stoic Week Handbook, we “can” find a “peaceful and trouble-free retreat” or citadel in our mind, but we must first “cut free of impressions that cling to the mind” (Med. 12.3, above). I take this to mean false impressions, or–and this is where it gets confusing, because even Marcus is apparently confused–false assumptions based on illogical conclusions from phantasiai.
Then the Med. 12.3 passage transitions directly into an exhortation to focus on the present and beware of the trappings of the past and future. I was initially confused by this, but it only takes a minor logical leap to equate anything that occurred in the past, or that might happen in the future, with a mere impression: memory always fails us, and our anxieties about the future are also impressions–basic functions of the mind, not necessarily leading to sound assumptions. At any rate, the present is all that we have, and if the pursuit of virtue is of utmost importance, then neither past nor future can truly help us in that regard.
To use a concrete example of examining and rejecting an impression: I dislike insects. Certain insects, I absolutely loathe and fear. At Stoicon, before Prof. Pigliucci’s afternoon workshop, I spotted a large flying bug, which I thought was a moth. It turned out to be a loathsome flying cockroach, which a woman in the front row courageously stomped on, justly depriving it of whatever dubious right to live it might have had. Phantasia: the cockroach is hideous. False assumptions: this sighting means there are many more, and more are possibly under my chair, and they may soon begin to crawl on me. But I quickly amended my thoughts. Is it rational (or even sane) to have these fears? As Marcus says, of body, breath, and mind, only my mind is under my control. Rationally I can acknowledge that the presence of one bug does not mean there are many more (there are more, because this is New York, but it doesn’t mean they’re right under my chair). Besides, what does this have to do with seeking virtue? Absolutely nothing. I put it out of my mind.
It is such a wondrous thing, to be able to use your mind for your own benefit, instead of allowing it to sabotage you. As Marcus Aurelius writes:
Your ability to control your thoughts–treat it with respect. It’s all that protects your mind from false perceptions–false to your nature, and that of all rational beings. It’s what makes thoughtfulness possible, and affection for other people, and submission to the divine. Med. 3.9
 Hadot believes–and appears to be correct–that Marcus Aurelius (writing in Greek, not his native tongue) sometimes conflates the word for impressions with the word for assumptions, so when he tells himself to erase his impressions, he really means to erase the mistaken assumptions that he draws from his impressions.