How do we know if the place we are living is suitable? If we're getting enough food and shelter? Or something more important?

From the Sutta...

3. “Here, bhikkhus, a bhikkhu lives in some jungle thicket.  While he is living there his unestablished mindfulness does not become established, his unconcentrated mind does not become concentrated, his undestroyed taints do not come to destruction, he does not attain the unattained supreme security from bondage; and also the requisites of life that should be obtained by one gone forth - robes, almsfood, resting place, and medicinal requisites - are hard to come by. The bhikkhu should consider thus: ‘I am living in this jungle thicket. While I am living here my unestablished mindfulness does not become established … I do not attain the unattained supreme security from bondage; and also the requisites of life … are hard to come by.’ That bhikkhu should depart from that jungle thicket that very night or that very day; he should not continue living there.

4. “Here, bhikkhus, a bhikkhu lives in some jungle thicket. While he is living there his unestablished mindfulness does not become established, his unconcentrated mind does not become concentrated, his undestroyed taints do not come to destruction, he does not attain the unattained supreme security from bondage; yet the requisites of life that should be obtained by one gone forth … are easy to come by. The bhikkhu should consider thus: ‘I am living in this jungle thicket. While I am living here my unestablished mindfulness does not become established … I do not attain the unattained supreme security from bondage; yet the requisites of life that should be obtained by one gone forth … are easy to come by. However, I did not go forth from the home life into homelessness for the sake of robes, almsfood, resting place, and medicinal requisites. Moreover, while I am living here my unestablished mindfulness does not become established … I do not attain the unattained supreme security from bondage.’ Having reflected thus, that bhikkhu should depart from that jungle thicket; he should not continue living there.

5. “Here, bhikkhus, a bhikkhu lives in some jungle thicket. While he is living there his unestablished mindfulness becomes established, his unconcentrated mind becomes concentrated, his undestroyed taints come to destruction, he attains the unattained supreme security from bondage; yet the requisites of life that should be obtained by one gone forth … are hard to come by. The bhikkhu should consider thus: ‘I am living in this jungle thicket. While I am living here my unestablished mindfulness has become established … I have attained the unattained supreme security from bondage; yet the requisites of life … are hard to come by. However, I did not go forth from the home life into homelessness for the sake of robes, almsfood, resting place, and medicinal requisites. Moreover, while I am living here my unestablished mindfulness has become established … I have attained the unattained supreme security from bondage.’ Having reflected thus, that bhikkhu should continue living in that jungle thicket; he should not depart.

6. “Here, bhikkhus, a bhikkhu lives in some jungle thicket. While he is living there his unestablished mindfulness becomes established, his unconcentrated mind becomes concentrated, his undestroyed taints come to destruction, he attains the unattained supreme security from bondage; and also the requisites of life that should be obtained by one gone forth - robes, almsfood, resting place, and medicinal requisites - are easy to come by. The bhikkhu should consider thus: ‘I am living in this jungle thicket. While I am living here my unestablished mindfulness has become established … I have attained the unattained supreme security from bondage; and also the requisites of life … are easy to come by.’ That bhikkhu should continue living in that jungle thicket as long as life lasts; he should not depart.

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Read the complete sutta in the Middle Lenght Discourses of the Buddha, published by Wisdom Publications.

From the sutta:
"Just as when the oil in a burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, its light is inconstant & subject to change. If someone were to say, 'The oil in that burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, but as for its light, that is constant, everlasting, eternal, & not subject to change': would he be speaking rightly?"

"No, venerable sir. Why is that? Because the oil in that burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, so how much more should its light be inconstant & subject to change."

Read the entire sutta...