1. That which takes the image of the thinker. When a man thinks of himself as in some distant place, or wishes earnestly to be in that place, he makes a thought-form in his own image which appears there. Such a form has not infrequently been seen by others, and has sometimes been taken for the astral body or apparition of the man himself. In such a case, either the seer must have enough of clairvoyance for the time to be able to observe that astral shape, or the thought-form must have sufficient strength to materialise itself--that is, to draw round itself temporarily a certain amount of physical matter. The thought which generates such a form as this must necessarily be a strong one, and it therefore employs a larger proportion of the matter of the mental body, so that though the form is small and compressed when it leaves the thinker, it draws round it a considerable amount of astral matter, and usually expands to life-size before it appears at its destination. 2. That which takes the image of some material object. When a man thinks of his friend he forms within his mental body a minute image of that friend, which often passes outward and usually floats suspended in the air before him. In the same way if he thinks of a room, a house, a landscape, tiny images of these things are formed within the mental body and afterwards externalised. This is equally true when he is exercising his imagination; the painter who forms a conception of his future picture builds it up out of the matter of his mental body, and then projects it into space in front of him, keeps it before his mind's eye, and copies it. The novelist in the same way builds images of his character in mental matter, and by the exercise of his will moves these puppets from one position or grouping to another, so that the plot of his story is literally acted out before him. With our curiously inverted conceptions of reality it is hard for us to understand that these mental images actually exist, and are so entirely objective that they may readily be seen by the clairvoyant, and can even be rearranged by some one other than their creator. Some novelists have been dimly aware of such a process, and have testified that their characters when once created developed a will of their own, and insisted on carrying the plot of the story along lines quite different from those originally intended by the author. This has actually happened, sometimes because the thought-forms were ensouled by playful nature-spirits, or more often because some 'dead' novelist, watching on the astral plane the development of the plan of his fellow-author, thought that he could improve upon it, and chose this method of putting forward his suggestions.