Firmamentum often gets precise meaning from a limiting genitive, which is also sometimes appositional: ossa nervique et articuli, firmamenta _totius corporis_, Sen. De Ira, 2, 1, 2; firmamenta _stabilitatis constantiaeque_ est eius quam in amicitia quaerimus fides, Lael. 65; eum _ordinem_ firmamentum ceterorum _ordinum_ recte esse dicimus, Pomp. 17; transversaria _tigna_ iniciuntur, quae firmamento esse possint, B. G. 2, 15, 2; firmamentum ac robur totius _accusationis_, Mur. 28, 58; firmamentum _rei publicae_, Planc. 9, 23; firmamentum _dignitatis_, T. 4, 7; inventa ratione firmamentum [_orationi_] quaerendum est, Inv. I, 34. Instrumentum is a word which has the most general meaning, and really receives less influence from its verb stem than from the context. Even when there is a qualifying genitive or other limiting factor it retains more or less of its general character. Probably its most definite meaning is that of furniture (of a house): decora atque ornamentum fanorum in instrumento ac _supellectili_ C. Verris nominabuntur, Verr. 2, 4, 44; instrumenti ne magni siet (of a _villa_), Cato, R. R. I. 5. A common meaning is that of a tool, or utensil of any kind: inest huic computationi sumptus fabrorum et _venatorii_ instrumenti, Plin. 3, 19; crudelia iussae instrumenta necis, _ferrumque ignisque_ parantur, Ov. M. 3, 697; _arma_, _tela_, _equos_ et cetera instrumenta militiae parare, Sall. Jug. 43, 3; naves _nautico_ instrumento aptae, Liv. 30, 10, 3. The following example shows it meaning a legal document: opus est intueri omne _litis_ instrumentum; quod videre non est satis, _perlegendum_ est, Quint. 12, 8, 12. The meaning of supply, provisions (both literal and figurative) is illustrated by the following examples: quid _viatici_, quid instrumenti satis sit, Att. XII, 32, 2; instrumenta _naturae_ deerant, sed tantus animi splendor erat ut.., Brut. 77, 268; in _oratoris_ vero instrumento tam lautam supellectilem numquam videram, De Or. I, 36, 165. In one instance it plainly means apparel, dress: in iuvenem rediit, _anilia_ demit instrumenta, Ov. M. 14, 766. The meaning of aid or assistance is seen in these citations: quanta instrumenta habeat _ad obtinendam_ adipiscendamque sapientiam, Leg. 1, 22; industriae _subsidia_ atque instrumenta virtutis in libidine audaciaque consumpsit, Cat. 2, 5.