CLASSIFICATION OP THINGS 113 objects of ownership ; and secondly, according to their nature, as corporeal and incorporeal, movable and immov- able.^ The significance of these distinctions will appear from the sequel. Things as objects of ownership. Justinian dis- Things as tinguishes things as (a) res communes, (6) res publicae, ownership, (c) res universitatis, {d) res nuUius, (e) res singulorum.^ A simpler arrangement would classify things as : A. Things legally incapable of ownership {res extra commercium). B. Things legally capable of ownership {res in commer- cio) ; which again are either : . Ownable in law, but unowned in fact {res nullius) ; or . O-wnable in law, and owned in fact ; whether (a) by individuals {res singulorum), or (6) by corporations and similar juristic persons {res universitatis). Things unownable. Things common and things public Things are legally incapable of ownership.^ To the class of ablT'^ things common, i.e. common to all mankind, are referred the air, flowing water, the sea, and the sea shore.* The Res oom- class of things public includes harbours,® public rivers or ^'J'res lakes ^ and public roads.' The distinction between things publicae. common and things public is not always maintained in the texts of the Roman Law,* and indeed is of small impor- tance. The substantial thing is that none of the above- mentioned things can be owned either by individuals or by corporations, i.e. they are all extra commercium. Thus, the air is insusceptible of ownership ; but it is not The air. inconsistent with this that a land-owner has certain rights in respect of the air incumbent on his land, so that, e.g.
Gr. 2. 1. 4. 2 ijjst. 2. 1. pr. ; Gr. 2. 1. 16 ; Voet, 1. 8. 1.
^ Voet, indeed, treats res publicae as res alicfjus soil, populi, but the arrangement in the text is preferable. Of. Dig. 41. 1. 14. pr.
- Inst. 2. 1. 1 ; Dig. 1. 8. 2 ; Gr. 2. 1. 17 and 21 ; Voet, 1. 8. 3.
Inst. 2. 1. 2. « Gr. 2. 1. 25-9 ; Van Leeuwen, 2. 1, 12.
' ' Herewegen.' Gr. 2. 36. 9 ; Oens. For. 1. 2. 14. 34. ' Voet, 8. 1.2. Thus in Inst. 2. 1. 1, we read: communia sunt omnium haec : aer et aqua profluens et mare et per hoc litora maris. But in Dig. 43. 8. 3. pr. Celsus says : Litora, in quae populus Romanus im- perium habet, populi Romani esse arbitror.
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