prima mobilia

Noun

primum mobile (plural primum mobiles or prima mobilia)

1. (historical) The outermost celestial sphere of the heavens in Ptolemaic astronomy, which was believed to cause all the inner spheres to rotate.
   • But as there is a double motion of the stars, that is, under the primum mobile, and round the world, by both which, as we have said, they influence, we must consequently suppose, that the significators rule over things subjected to them by this twofold (or double) motion, to wit, under the primum...[1814], Didacus Placidus de Titus [i.e., Placido Titi], “Theses, from the First Book of the Author’s ‘Celestial Philosophy’”, in John Cooper, transl., Primum Mobile, with Theses to the Theory, and...
2. The prime mover or first cause (“an initial cause from which all other causes and effects follow”).
   • Have we got among our primum mobiles the force of such elastic vapours as be generated for the purpose out of nonelastic substances, and are not incondensible? A good magazine of vitr[iolic] acid and powder'd marble would not only save the expence of air in feeding fire, but generate heat.1779 January 20–22, Jeremy Bentham, “302: To Samuel Bentham: 20–22 January 1779 (Aet 30)”, in Timothy L[auro] S[quire] Sprigge, editor, The Correspondence of Jeremy Bentham (The Collected Works of...

   Synonyms:

   primus motor

3. (broadly) The person or thing that is the main impetus for some action; a driving force.
   • The great wheels, the primum mobiles, that have gone so violently and brought us into this confusion, I move that you will proceed against them, and that the king's gracious intentions may have farther effect, and those only excepted.1689 May 23, Robert Cotton, “Debate on the Heads for a Bill of Indemnity”, in Cobbett’s Parliamentary History of England. From the Norman Conquest, in 1066, to the Year 1803. […], volume V...