SB 3.26.34

bhūtānāṁ chidra-dātṛtvaṁ
 bahir antaram eva ca
prāṇendriyātma-dhiṣṇyatvaṁ
 nabhaso vṛtti-lakṣaṇam
Word for word: 
bhūtānām — of all living entities; chidra-dātṛtvam — the accommodation of room; bahiḥ — external; antaram — internal; eva — also; ca — and; prāṇa — of the vital air; indriya — the senses; ātma — and the mind; dhiṣṇyatvam — being the field of activities; nabhasaḥ — of the ethereal element; vṛtti — activities; lakṣaṇam — characteristics.
Translation: 
The activities and characteristics of the ethereal element can be observed as the accommodation of room for the external and internal existences of all living entities, namely the field of activities of the vital air, the senses and the mind.
Purport: 

The mind, the senses and the vital force, or living entity, have forms, although they are not visible to the naked eye. Form rests in subtle existence in the sky, and internally it is perceived as the veins within the body and the circulation of the vital air. Externally there are invisible forms of sense objects. The production of the invisible sense objects is the external activity of the ethereal element, and the circulation of vital air and blood is its internal activity. That subtle forms exist in the ether has been proven by modern science by transmission of television, by which forms or photographs of one place are transmitted to another place by the action of the ethereal element. That is very nicely explained here. This verse is the potential basis of great scientific research work, for it explains how subtle forms are generated from the ethereal element, what their characteristics and actions are, and how the tangible elements, namely air, fire, water and earth, are manifested from the subtle form. Mental activities, or psychological actions of thinking, feeling and willing, are also activities on the platform of ethereal existence. The statement in Bhagavad-gītā that the mental situation at the time of death is the basis of the next birth is also corroborated in this verse. Mental existence transforms into tangible form as soon as there is an opportunity due to contamination or development of the gross elements from subtle form.