"I am the worker. I am doing this. I am flying. I am going there. I am riding the path(?). I am working. I..." "I" is there. This "I" false ego is there. Ahaṁ mameti (SB 5.5.8). So forgetting Kṛṣṇa, when we concentrate only "I" and "mine," that is material world. That is material world. Material means separated. When I create, when we forget Kṛṣṇa, when I create "I" and "mine," that is material. Make it clear.(?) Otherwise, īśāvāsyam idaṁ sarvam (ISO 1).
Everything is Kṛṣṇa's energy. Kṛṣṇa is spiritual, so His energy is also spiritual. But in the spiritual energy there is the possibility of forgetting Kṛṣṇa. That is called material energy. So if we remember Kṛṣṇa, that is not material energy. A man, stone, wood, brick and constructs a big, high skyscraper building; that is material energy. But the same stone, same wood, same cement, you construct a very nice temple of Kṛṣṇa, that is spiritual energy. Now, the question is how the woods and stones which is matter, becomes spiritual. Is not that the question? We say one man is constructing big skyscraper building with woods and stones, we say this is materialism. But they can also challenge you that "You are also interested in woods and stones and constructing a big church or temple. Why is your idea spiritualism?" Now, you can compare. This is spiritualism means in this stone and earth and woods you remember Kṛṣṇa, "I am constructing something for Kṛṣṇa." Therefore it is spiritualism.