Dear Harry,
The image is definitely widespread in Buddhist materials, both tantric and non-tantric. One of the five aspects of the Buddha's gnosis (pañcajñāna) is "mirror-like gnosis" (ādarśajñāna), in which, according to the ca. 4th century
Mahāyānasūtrālaṃkāra (Bodhyadhikāra)
« Le
miroir spirituel », Sinologica, I, 2, Basel, 1947,, pp. 112-137,
Given the intertextuality between later Indian Buddhism and Kashmir Saivism, it is not surprising that the metaphor would be found in the latter sources as well.
hope this helps to get you started,
Matthew
viśvaṁ darpaṇa-dṛśyamāna-nagarī-tulyaṁ nijāntar-gataṁ
paśyann-ātmani māyayā bahir ivodbhutaṁ yathā nidrayā
yaḥ sākṣāt kurute prabodha-samaye svātmanam evādvayaṁ
tasmai śri-guru-mūrtaye nama idaṁ śri-dakṣināmūrtaye
One of the reasons Amarhath Rai in his article "The Daksinamurti Hymn and the Manasollasa published in Vol. 6 of The Journal of Oriental Research, Madras, 1932 gives for rejecting Sankaracarya as the author is the metaphor in the first verse of the world as an image in a mirror.
Does this metaphor of the world as an image in a mirror only appear in Kashmir Shaivite writings or does it occur in the writings of other religous or philosophical schools.
Thanks,
Harry Spier