They are not material. His impersonality therefore is a negation of His materiality, but not a denial of His transcendental personality.
"Brahman ultimately refers to the Personality of Godhead. Impersonal Brahman realization is just the negative conception of the mundane creations. Paramātmā is the localized aspect of Brahman within all kinds of material bodies. Ultimately the Supreme Brahman realization is the realization of the Personality of Godhead according to all evidence of the revealed scriptures. He is the ultimate source of viṣṇu-tattvas.
"The Purāṇas are also supplementary to the Vedas. The Vedic mantras are too difficult for an ordinary man. Women, śūdras and the so-called twice-born higher castes are unable to penetrate into the sense of the Vedas. And thus the Mahābhārata as well as the Purāṇas are made easy to explain the truths of the Vedas.