He who simultaneously knows both Vidya and Avidya gets over Death by Avidya and attains immortality by Vidya.
Q12-1) How to overcome the darkness caused by following path of vidya and avidya ?
Avidya stands for ignorance. All activities secular or religious performed with a desire for happiness in this world or hereafter fall under the category of avidya. In other words avidya stands for selfish actions and rituals blindly followed in pursuit of happiness. This is also called kamya karma. Vidya stands for meditations (upasana) on deities.
If it karma is Avidya, why Vedas have prescribed duties in karmakanda ? In order to help jiva to move from inertia (tamas) to activity (rajas) duties are prescribed. Also vedas indicate result of performance of rituals in this life and here after. This is done to help a person with predominant tamo and rajo guna to gain success and understand limitation of success and gradually rise to satva guna preparing oneself for SELF knowledge.
Avidya can be over come by performing unselfish acts (nishkama karma). Same action social or religious performed as an offering to the Lord (Isha) with a sole intention of purification of impressions purifies the person. Gradual purification (chitta shuddhi) is the result of unselfish actions (nishkama karma). In this process, the person crosses over the world of death of earthly plane which is called mrityu loka. Blindly following rituals one goes to world of ancestors ( manes) and born in earthly plane again and again. By Nishkama karma he/she becomes free from world of manes.
On the other hand a person following vidya (upasana) of minor deities, attains the world of those deities (deva loka). He/she enjoys the pleasure of those worlds and returns to earthly plane. However, if perfoms upasana as unselfish activity without desire for any heavenly planes but just for the purpose of purification of subconscious impressions, he becomes free from binding vasanas of enjoyment of pleasures. He crosses over rajo guna and establishes himself in satva guna. Here amritatva also can mean that he merges with the deity (sayujya).
Both pursuit of karma and upasana in a unselfish manner is required for gradual liberation or krama mukti.
He develops qualities required for SELF knowledge – sadhana chatusthaya and attains SELF knowledge through para vidya.
This is the teaching of Rishis.
विद्यां चाविद्यां च यस्तद्वेदोभयं सह ।
अविद्यया मृत्युं तीर्त्वा विद्ययामृतमश्नुते ॥ ११ ॥
vidyāṃ cāvidyāṃ ca yastadvedobhayaṃ saha |
avidyayā mṛtyuṃ tīrtvā vidyayāmṛtamaśnute || 11 ||