His Divine Grace A.C. Bhaktivedanta Swami Prabhupada : The same building, the same dictaphone, the same typewriter, same table, same chair, when they are used for Krsna, it is spiritual.

Prabhupāda: Yes, it is the activity which concerns. In the university there is only activity of education, learning. And here, all the criminals are violating the laws, they are put together. But superficially they look the same room, same food, same office, same typewriter. So it is the question of understanding why it is called criminal department and why it is called university. So as soon as it is university department, that is good. The same building, the same dictaphone, the same typewriter, same table, same chair, when they are used for Kṛṣṇa, it is spiritual. The same money, everything, it looks like that. Therefore they cannot understand. The nirviśeṣavādī and the śūnyavādī, they: "Spiritual means these things should be zero." They say it should be zero. "No table, no chair, no house, no, no, no, no..." But that is (laughs) ignorance. Prāpañcikatayā buddhyā hari-sambandhi-vastunaḥ. The things which are usable by Kṛṣṇa consciousness movement, if we give up them, prapañcikā, as material, that is foolishness. That they do not know. They have yet to learn. It is Rūpa Gosvāmī's injunction. Prāpañcikatayā buddhyā hari-sambandhi-vastunaḥ, mumukṣubhiḥ parityāgaḥ. Parityāga means giving up: "Oh, it is material." So we are not such fools, śūnyavādī and nirviśeṣavādī. We are not such fools. Arjuna, he thought that not killing is better than killing, but Kṛṣṇa convinced him, "Yes, killing is better than not killing." Therefore he, after reading Bhagavad-gītā, he took it, "Yes, killing is better than not killing." Generally people understand not killing is better than killing. But Kṛṣṇa explained to Arjuna, "No, if there is My desire, then killing is better than not killing." And that is knowledge. Therefore we have to carry out simply Kṛṣṇa's order or His representative's order. Then it is all good. Either killing or not killing, it doesn't matter because it is coming directly from the Supreme. And that is spiritual. Otherwise why Kṛṣṇa induced Arjuna to kill? He was presenting as very good man, that "I shall not kill." And that's.... Actually that is good. Even if you enemy excuse him, that is very good idea. But if it is not desired by Kṛṣṇa, then it is bad. So our principle is: We have to act according to the desire of Kṛṣṇa. Then it is good; otherwise bad. Kṛṣṇa says, na māṁ duṣkṛtino mūḍhāḥ prapadyante narādhamāḥ (BG 7.15). So in spite of advancement of knowledge, because they are not Kṛṣṇa conscious, therefore they are all duṣkṛtinaḥ, all sinful men. That is the test. So it is very difficult to understand this philosophy, but this is the fact. We are not going to be followers of zero-vādīs or impersonal-vādīs. We remain completely in the varieties, but these varieties are usable only for the satisfaction of Kṛṣṇa. That is spiritual. You cannot stop the varieties. You have to change the quality of the varieties. Just like we are eating. It is not possible to stop eating. Why shall I stop eating? But the quality is changed. It is prasādam.

Source : https://vaniquotes.org/wiki/The_same_building,_the_same_dictaphone,_the_same_typewriter,_same_table,_same_chair,_when_they_are_used_for_Krsna,_it_is_spiritual

How “material” things can be spiritualized–SP :

Source : https://krishnaconsciousnessmovement.com/?p=30123