Yajña the master key word in the 4th chapter

Our journey takes us to the 4th chapter. The Master key word of this chapter is Yajña . With this one key, we can unlock doors to many secret chambers in this chapter. Krishna has portrayed five types of Yajña in the following Shloka.

द्रव्ययज्ञास्तपोयज्ञा योगयज्ञास्तथापरे।

स्वाध्यायज्ञानयज्ञाश्च यतयः संशितव्रताः॥गीता ४-२८॥

Yajña  is described in a very broad perspective in this Shloka. All constructive activities done using body, speech and mind come under one definition.  The five types of Yajña s are

•  Dravya Yajña (outwardly focused Yajña )
• Tapo Yajña
• Yoga Yajña
•  Swadhyaya Yajña
•  Jnana Yajña

Dravya Yajña :

Yajña  has two faces, internal and external; Dravya Yajña is the external form of Yajña. This external Yajña needs purity at different levels. First is Yajamana Shuddi which is the purity of the performer. Next is the Havis Shuddi, pure medicinal plants along with desi cow ghee should be used as havis. Agni the fire should also be pure, called as Agni Shuddi. Agni generated by rubbing (mathana) Shammi wood logs called as Arani janya or by using sunlight and lens called as Suryakanta janya are the preferred options. Next best option is to borrow Agni from a house where Agnihotra is being practiced continuously. Last option would be to take it from one's own kitchen. After Yajamana shuddi, Havis shuddi and Agni shuddi, next is Bhoomi shuddi (purity of the place) and Mantra shuddi (appropriate Mantras with correct pronunciations).

Tapo Yajña :

Krishna talks about three types of tapas in 17th chapter. Sharirika (with body) tapas, Vachika (with speech) tapas, and Manasika (mind) tapas.

देवद्विजगुरुप्राज्ञपूजनं शौचमार्जवम् ।
ब्रह्मचर्यमहिंसा च शारीरं तप उच्यते ॥ गीता १७- १४॥
Respecting gods, elders and learned people, maintaining purity, simplicity, Brahmacharya and Ahimsa are the requirements of Sharirika Tapas.

अनुद्वेगकरं वाक्यं सत्यं प्रियहितं च यत् ।
स्वाध्यायाभ्यसनं चैव वाङ्मयं तप उच्यते ॥ गीता १७- १५॥
Speech which does not create anxiety in others, truthful, constructive, pleasant and always backed up by self-study is Vachika tapas.

मनः प्रसादः सौम्यत्वं मौनमात्मविनिग्रहः ।
भावसंशुद्धिरित्येतत्तपो मानसमुच्यते ॥ गीता १७- १६॥

Pleasant mind, mild, peaceful, silent, self-restrained, purity of thoughts and emotions are the dimensions of Manasika tapas.