The first vibration of creation is called Shivatattva

निजेच्छया जगत्सृष्टमुद्युक्तस्य महेशितुः |
प्रथमो यः परिस्पन्दः शिवतत्त्वं तदुच्यते || 70 ||

While the great God was occupied with creating the universe of his own wish, the first vibration which (occurred) is called the Shiva element.

Only by the combination of Lord Shiva and Goddess Shakti does joy arise continuously

शिवतत्त्ववर्णनं नाम षोडशोऽध्यायः

Shiva element description Chapter 16

सुब्रह्मण्य उवाच |

Kartikeya said (to sage Vamadeva)

एवं शिवत्वं शक्तित्वं परमात्मनि दर्शितम् |
शिवशक्त्योस्तु संयोगादानन्दं सततोदीतः || 33 ||
अतो मुने तमुद्दिश्य मुनयः क्षीणकल्मषाः |
शिवे मनः समाधाय प्राप्तः शिवमनामयम् || 34 ||

In this way, the characteristics of Lord Shiva and Goddess Shakti are shown in the supreme soul. Only by the combination of Lord Shiva and Goddess Shakti does joy arise continuously.
Sage, therefore considering that, sages who have become free of sin, having focussed their mind on Lord Shiva, achieved the pure Shiva state.

Three forms of the supreme Goddess disciples should meditate upon daily

तदीयं त्रिविधं रूपं स्थूलं सूक्ष्मं परं ततः |
ध्येयं मुमुक्षुभिर्नित्यं क्रमतो योगिभिर्मुने || 13 ||
Sage, these three forms of that (supreme Goddess Shivaa), gross, subtle and higher than that, should be meditated upon by renunciate disciples (those aspiring for liberation) always/everyday; successively by Yogis.

The all pervading supreme Goddess Shakti/Shivaa is reachable by devotion/affection

यस्य पुंसां परा शक्तिर्भावगम्या मनोहरा |
निर्गुणा स्वगुणेरैव निगूढा निष्कला शिवा || 12 ||

The Purusha’s (God’s) higher energy Shivaa is reachable by affection, attractive, formless, hidden by her own characteristics only, all pervading.

The whole universe is lighted up by the God of everyone

यस्य भासा विभातीदञ्जगत्सर्वं समन्ततः |
सर्वैश्वर्येण संपन्नो नाम्ना सर्वेश्वरः स्वयम् || 10 ||
With whose brilliance, this whole universe is lighted up from all sides, is the God of everyone himself, endowed with all characteristics of Godliness.

The main meaning of Pranava

प्रणवार्थः शिवः साक्षात्प्राधान्येन प्रकीर्तितः | श्रुतिषु स्मृतिशास्त्रेषु पुराणेष्वागमेषु च || 6 ||

The main meaning of the Pranava (Om, the primordial sound) is said to be Shiva in visible form, in Shrutis, Smritis, Puranas and Agamas.

People do not know the great God

संन्यासविधिवर्णनं नाम द्वादशोऽध्यायः

Renunciation procedure description Chapter 12

श्रीब्रह्मण्य उवाच |

Kartikeya said (to sage Vamadeva)

न जानन्ति परम् साक्षात्प्रणवार्थं महेश्वरम् |
सगुणं निर्गुणं ब्रह्म त्रिदेवजनकं परम् || 4 ||

(Living beings under the influence of Maya) do not know the highest great God in visible form, the meaning of the Pranava (Om, the primordial sound), with form as well as without form, the supreme element and the father of the three Devas (Brahma, Vishnu and Shiva).