With the secret form|
[Answer] All the ordinary ideas, ie of duality, etc are only true for a time, but non-duality is ever true. This [non-duality] is most secret [guhya] not perceivable by ordinary vision; rUpa, the form [her nature]. The Su-sam [IV. 47. 69] says, "We adore Devi who assumes the form of the guru, secret in the form of secret knowledge, beloved by her secret devotees, residing in the secret place" Thus by attributing two forms to the one BrAhman the two kinds of scriptures are reconciled. Guhya means the Guhya Up. which is her form. The KUrma Pr. in describing the glory of Devi says, "Among the Upanisads, O Devi you are the Guhyopanisad"
 Her form is secret, beyond the senses. She is the Power and Truth, Satta, behind the phenomenal Universe, and hence She is unseen
Alternatively, there is an Upanisad by the name Guhyopanist; She is that also.