I'm trying to understand how what the Pilgrim engages in isn't imaginative prayer. In chapter 2, when he's spending the summer in the forester's hut, he achieves self-acting prayer in the heart as follows:
"I set about reading The Philokalia in the exact order [my starets] had bidden. I read it once, and again a second time, and this reading kindled in my soul a zealous desire to make what I had read a matter of practical experience. I saw clearly what interior prayer means, how it is to be reached, what the fruits of it are, how it filled one's heart and soul with delight, and how one could tell whether that delight came from God, from nature or from temptation.
"So I began by searching out my heart in the way Simeon the New Theologian teaches. With my eyes shut I gazed in thought, i.e., in imagination, upon my heart. I tried to picture it there in the left side of my breast and to listen carefully to its beating. I started doing this several times a day, for half an hour at a time, and at first I felt nothing but a sense of darkness. But little by little after a fairly short time I was able to picture my heart and to note its movement, and further with the help of my breathing I could put into it and draw from it the Prayer of Jesus in the manner taught by the saints, Gregory of Sinai, Callistus and Ignatius. When drawing the air in I looked in spirit into my heart and said, 'Lord Jesus Christ,' and when breathing out again, I said, 'Have mercy on me.' " (emphasis mine)
This looks to me like he's imagining his heart while praying the Jesus Prayer. However, later in the book, in chapter 4, he cautions a fellow traveler, who has gone blind in his old age, against imaginative prayer, even as he instructs him in how to achieve self-acting interior prayer via imagination:
" '...can you not picture your hand or your foot as clearly as if you were looking at it, can you not turn your eyes to it and fix them upon it, blind as they are?'
" 'Yes, I can,' he answered.
" 'Then picture to yourself your heart in just the same way, turn your eyes to it just as though you were looking at it through your breast, and picture it as clearly as you can. And with your ears listen closely to its beating, beat by beat. When you have got into the way of doing this, begin to fit the words of the Prayer to the beats of the heart one after the other, looking at it all the time. Thus, with the first beat, say or think "Lord," with the second, "Jesus," with the third, "Christ," with the fourth, "have mercy," and with the fifth "on me." And do it over and over again. This will come easily to you, for you already know the groundwork and the first part of praying with the heart. Afterwards, when you have grown used to what I have just told you about, you must begin bringing the whole Prayer of Jesus into and out of your heart in time with your breathing, as the Fathers taught. Thus, as you draw your breath in, say, or imagine yourself saying, "Lord Jesus Christ," and as you breathe out again, "have mercy on me." Do this as often and as much as you can, and in a short space of time you will feel a slight and not unpleasant pain in your heart, followed by a warmth. Thus by God's help you will get the joy of self-acting inward prayer of the heart. But then, whatever you do, be on your guard against imagination and any sort of visions. Don't accept any of them whatever, for the holy Fathers lay down most strongly that inward prayer should be kept free from visions, lest one fall into temptation.' "
How is this picturing of the heart while saying the Jesus Prayer distinct from using imagination in prayer?
