The man who sees the celestials while sleeping or while he is awake soon turn mad. The spirits under whose influence this happens, are called the celestial spirits.
यः पश्यति नरो देवान् जाचद् वा शयितोऽपि वा। उन्माद्यति स तु क्षिप्रं तं तु देवग्रहं विदुः॥