Moreover, the oil lamp in Hinduism is considered as Goddess Mother. The light produced by the lamp could create illumination of spiritual insight or the divinity within. Thus, lighting a lamp is like an invitation to Goddess Mother to come and bless us.
The scriptures inform that while lighting the oil lamp one should chant the following Sanskrit verse to invoke the divine energy: Subham Karoti Kalyanam / Arogyam Dhana Sampadah / Shatru Buddhi Vinashaya / Deepa Jyotir Namostute. This verse means somewhat like the following: my salutations to the light of the lamp, which brings auspiciousness, health and prosperity; and which destroys inimical feelings.
After lighting the lamp, chant the following verse: Deepajyoti Parabrahma/ Deepajyoti Janardhana/ Deepo me hara tu paapam/ Deepa Jyothir Namostute. The close meaning this verse in English is: my salutations to the lamp; whose light is the Knowledge Principle, which dispels the darkness of ignorance and by which all can be achieved in life.
The spiritual message from a lighted lamp has been explained in the following verse: Vairagya taila sampurne bhakti varti samanvite/ Prabodha purnapatre tu gnapti deepam vilokayet. It means that the oil in the lamp is the renunciation from the material world, the flame is the divine light of wisdom and the cotton wick is devotion to bring us closer to liberation.
Thus, in nutshell, the spiritual meaning of Diwali is to heighten one’s awareness of inner light and make liberation as the ultimate aim of life.