A lucus was a cultivated place, more like a wooded park than a forest, and might contain an aedes, a building that housed the image of a god, or other landscaped features that facilitated or gave rise to ritual.
Apuleius records that "when pious travelers happen to pass by a sacred grove (lucus) or a cult place on their way, they are used to make a vow (votum), or a fruit offering, or to sit down for a while.
[7] Servius, however, somewhat perversely says that a lucus is so called because non luceat, "it is not illuminated", perhaps implying that a proper sacred grove hosted only legitimate daytime ceremonies and not dubious nocturnal rites that required torchlight.
[11] It is tempting, but misleading, to read ecological principles into ritualized agriculture; for the early Romans, respect was the partner of fear in their regard for the divine forces in nature, and the open invocation with which this prayer begins is a contractual "out" or hedge.
[13] Thoreau nonetheless made admiring reference to Cato's prayer in Walden: "I would that our farmers when they cut down a forest felt some of that awe which old Romans did when they came to thin, or let in the light to, a consecrated grove (lucum conlucare).