"To the yogin who attends to the incoming breath with mind that is cleansed of the nine lesser defilements the image arises with a pleasant feeling similar to that which is produced in the action of spinning cotton or silk cotton. Also, it is likened to the pleasant feeling produced by a breeze. Thus in breathing in and out, air touches the nose or the lip and causes the setting-up of air perception mindfulness. This does not depend on colour or form. This is called the image. If the yogin develops the image [sign] and increases it at the nose-tip, between the eyebrows, on the forehead or establishes it in several places, he feels as if his head were filled with air. Through increasing in this way his whole body is charged with bliss. This is called perfection.
And again, there is a yogin: he sees several images from the beginning. He sees various forms such as smoke, mist, dust, sand of gold, or he experiences something similar to the pricking of a needle or to an ant's bite. If his mind does not become clear regarding these different images, he will be confused [!]. Thus he fulfils overturning and does not gain the perception of respiration. If his mind becomes clear, the yogin does not experience confusion. He attends to respiration and he does not cause the arising of other perceptions [underlining mine]. Meditating thus he is able to end confusion and acquire the subtle image [sign]. And he attends to respiration with mind that is free. That image [sign] is free. Because that image [sign] is free, desire arises. Desire being free, that yogin attends respiration with equipoise. Equipoise, desire and joy being free, he attends to respiration, and his mind is not disturbed. If his mind is not disturbed, he will destroy the hindrances, and arouse the meditation (jhana) factors. Thus this yogin will reach the calm and sublime fourth meditation, jhana. This is as was fully taught above."http://www.arrowriver.ca/dhamma/nimitta.html
From what I get from this is that there are nimittas of unskillful and skillful means?viewtopic.php?f=23&t=2770
"In the same way, a monk intent on heightened mind should attend periodically to three themes: he should attend periodically to the theme of concentration; he should attend periodically to the theme of uplifted energy; he should attend periodically to the theme of equanimity. If the monk intent on heightened mind were to attend solely to the theme of concentration, it is possible that his mind would tend to laziness. If he were to attend solely to the theme of uplifted energy, it is possible that his mind would tend to restlessness. If he were to attend solely to the theme of equanimity, it is possible that his mind would not be rightly centered for the stopping of the fermentations. But when he attends periodically to the theme of concentration, attends periodically to the theme of uplifted energy, attends periodically to the theme of equanimity, his mind is pliant, malleable, luminous, and not brittle. It is rightly centered for the stopping of the fermentations."
I find this to be very accurate.http://www.accesstoinsight.org/tipitaka ... .than.html
Not much to say about this one...http://measurelessmind.ca/nimitta.html
From my experience and from reading about the topic, I would state that nimittas are simply reflections of the mind. So are nimittas acquired through unskillful nimittas that are experienced outside of meditation? Am I just getting hung up on labels? I was just wondering why someone might experience nimittas outside of meditation..
Watch the frog.