Devotees engage in the temple in the service of the Lord as arca-vigraha, a form made of material objects such as stone, metal, wood, jewels or paint. All of these are called sthula, or physical representations

Expressions researched:
"Therefore devotees engage in the temple in the service of the Lord as arcā-vigraha, a form made of material objects such as stone, metal, wood, jewels or paint. All of these are called sthūla, or physical representations"

Srimad-Bhagavatam

SB Canto 4

Worship of the arcā-vigraha is not idol worship. The arcā-vigraha is an incarnation of the Lord in a form appreciable by a devotee. Therefore devotees engage in the temple in the service of the Lord as arcā-vigraha, a form made of material objects such as stone, metal, wood, jewels or paint. All of these are called sthūla, or physical representations.

SB 4.12.17, Translation and Purport

In Badarikāśrama Dhruva Mahārāja's senses became completely purified because he bathed regularly in the crystal-clear purified water. He fixed his sitting position and by yogic practice controlled the breathing process and the air of life; in this way his senses were completely withdrawn. Then he concentrated his mind on the arcā-vigraha form of the Lord, which is the exact replica of the Lord and, thus meditating upon Him, entered into complete trance.

Here is a description of the aṣṭāṅga-yoga system, to which Dhruva Mahārāja was already accustomed. Aṣṭāṅga-yoga was never meant to be practiced in a fashionable city. Dhruva Mahārāja went to Badarikāśrama, and in a solitary place, alone, he practiced yoga. He concentrated his mind on the arcā-vigraha, the worshipable Deity of the Lord, which exactly represents the Supreme Lord, and thus thinking constantly of that Deity, he became absorbed in trance. Worship of the arcā-vigraha is not idol worship. The arcā-vigraha is an incarnation of the Lord in a form appreciable by a devotee. Therefore devotees engage in the temple in the service of the Lord as arcā-vigraha, a form made of material objects such as stone, metal, wood, jewels or paint. All of these are called sthūla, or physical representations. Since the devotees follow the regulative principles of worship, although the Lord is there in His physical form He is nondifferent from His original, spiritual form. Thus the devotee gets the benefit of achieving the ultimate goal of life, that is to say, becoming always absorbed in thought of the Lord. This incessant thought of the Lord, as prescribed in the Bhagavad-gītā, makes one the topmost yogī.