The “brilliant golden lid” referred to in the Isha Upanishad describes an experience of consciousness by those who seek to achieve a higher state of conscious awareness than the mental-vital-physical mechanism under which most people operate. This has also given rise to the concept of there being two “hemispheres” of consciousness, the lower and the higher, separated by an intermediary level that translates the principle of the one into the principle of the other, similar to a “step down transformer” in terms of electricity generation and distribution. The upper hemisphere of Sat-Chit-Ananda is translated, through the action of the supramental level of consciousness, from its status of Oneness, All-Knowledge and All-Power and All-Bliss into the multitude of names, forms and forces that we recognize as separate in the lower hemisphere through the action of mind, but which are in reality forms, forces and beings that abide forever in inherent Oneness.
The effort to penetrate the veil or lid can take a number of forms, including the austere concentration of the Yoga of Knowledge, the devotional absorption of the Yoga of Love, or the dedicated focused Will and surrender of the Yoga of Works. It may also take the form of prayer and fasting, vision quest, or practices such as Hatha Yoga, Kundalini Yoga or Raja Yoga that seek to control and direct the psychic Prana, the vital force of all creation, to direct the energy upwards and pierce through to the other side.
Depending on which method succeeds, the seeker will see the Divine in a different form or as a different principle. Sri Aurobindo elaborates: “But when it succeeds in that difficult endeavour, it sees the divine as something superior to it, distant, high, conceptually, vitally, even physically above it, to which it looks up from its own humble station and to which it has, if at all that be possible, to rise, or if it be not possible, to call that down to itself, to be subject to it and to adore. It sees the divine as a superior plane of being, and then it regards it as a supreme state of existence, a heaven or a Sat or a Nirvana according to the nature of its own conception nor realisation. Or it sees it as a supreme Being other than itself or at least other than its own present self, and then it calls it God under one name or another, and views it as personal or impersonal, qualitied or without qualities, silent and indifferent Power or active Lord and Helper, again according to its own conception or realisation, its vision or understanding of some side or some aspect of that Being. Or it sees it as a supreme Reality of which its own imperfect being is a reflection or from which it has become detached, and then it calls it Self or Brahman and qualifies it variously, always according to its own conception or realisation,–Existence, Non-Existence, Tao, Nihil, Force, Unknowable.”
Sri Aurobindo, The Synthesis of Yoga, Part Two: The Yoga of Integral Knowledge, Chapter 13, The Difficulties of the Mental Being, pp. 377-378