Dig. 9.2.31

Paulus 10 ad sab.

Si putator ex arbore ramum cum deiceret vel machinarius hominem praetereuntem occidit, ita tenetur, si is in publicum decidat nec ille proclamavit, ut casus eius evitari possit. sed mucius etiam dixit, si in privato idem accidisset, posse de culpa agi: culpam autem esse, quod cum a diligente provideri poterit, non esset provisum aut tum denuntiatum esset, cum periculum evitari non possit. secundum quam rationem non multum refert, per publicum an per privatum iter fieret, cum plerumque per privata loca volgo iter fiat. quod si nullum iter erit, dolum dumtaxat praestare debet, ne immittat in eum, quem viderit transeuntem: nam culpa ab eo exigenda non est, cum divinare non potuerit, an per eum locum aliquis transiturus sit.

If a person who was pruning tress threw down a branch and killed a passing slave, the pruner if clearly liable if the branch fell on public land and if he did not call out so that an accident might have been avoided.  But Mucius also said that if this occurred on private land, there could be an action for culpa.  A person is culpable when a careful person (diligens) could have foreseen a danger.  A person is also culpable if he had called out only when the danger could not be avoided.  According to this reasoning, there is not much difference between a path over public and private land, since paths often go through private land.  If there was no path, he is only liable for dolus.