The Deity Form of The Lord
You want to see God through your material eyes, so God manifests through matter in the form of a deity.
Effect of Chanting The Hare Krishna Maha Mantra
The holy name of Krishna is so attractive that anyone who chants it — including all living entities, moving and nonmoving, and even Lord Krishna Himself — becomes imbued with love of Krishna. This is the effect of chanting the Hare Krishna maha-mantra.
Chaitanya Caritamrta, Antya Lila 3.268,
Srila Prabhupada
Material Enjoyment
When we see beautiful thing, what is it? It is just some light entering into our eyes and it is making us mad. Some frequency entering our ear & we get mad. Something scraping our tongue which is just a lump of flesh wiggling around. But when something touches its surface we go mad. This is material enjoyment & we take it seriously.
Effect of Rendering Devotional Service
By rendering devotional service unto the Personality of Godhead, Sri Krishna, one immediately acquires causeless knowledge and detachment from the world. — Srimad Bhagavatam, 01.02.07.