{1d08_aeternus, aeternitas}

Meaning Eternity is defined by calling eternal every thing from the definition (= essence) of which, on its own, follows its existence (the mantra, Ethica's hub mantra is: essentia involvit existentiam). Also linked are forms of remanere (remaining) when referring to the part of the human mind claimed eternal.
Subsets (kinds) causa sui = absolutely infinite, a special type of eternal
Mantras [what is] sub specie aeternitatis concipere
Dei aeternam et infinitam essentiam
Related concepts aeternus = [prf eqv] infinitus. A concept slightly stronger than infinitus, exclusively applying to God = natura-sense 2 = substance, is absolute infinitus Absolute infinitus = Causa per se = [mng-eqv] causa sui.
Occurrence [geomap]  Preoccurs from {1d06}
{1d01  causa sui}                                                                                  ... causa sui defined equivalent to eternal (as becomes clear in the next quote) ...  (but later some eternal things like attributes  turn out NOT to be called causa sui)  ...
 ... that which is self-caused ... that of which the essence involves existence, or that of which the nature is only conceivable as existent.  ... causam sui ... id cujus essentia involvit existentiam sive [mng-eqv] id cujus natura non potest concipi nisi existens.
{1d08 aeternitas}                                                                               ... "Eternity" defined by calling "eternal" a thing from the essence (= definition) of which follows its existence ... more:  see notes-quote of {1p19} ...
 ... By eternity, I mean existence itself, in so far as it is conceived necessarily to follow solely from the definition of that which is eternal.  ... Per aeternitatem intelligo ipsam existentiam quatenus ex sola rei  aeternae definitione necessario sequi concipitur.
{1p19 Deus aeterna}                                                                       ... {1p07} "Ad naturam  substantiae pertinet existere", used here as a premiss for proof and rephrased for the purpose using aeternus and aeternitas ... hence saying that "it belongs to the nature (=essence) of something to exist" means saying it is eternal   ...
 ... God, and all the attributes of God, are eternal.  ... Deus sive [non-excl non-exh] omnia Dei attributa sunt aeterna.
 ... eternity appertains to the nature of substance  ...  therefore, eternity must appertain to each of the attributes, and thus all are eternal.  ... ad naturam  substantiae pertinet aeternitas. Ergo unumquodque attributorum aeternitatem involvere debet adeoque omnia sunt aeterna ...
{2p44c2 aeternitatis specie}                                                         ... eternity and the nature of reason ...
 ... It is in the nature of reason to perceive things under a certain form of eternity ...  ... De natura rationis est res sub quadam aeternitatis specie percipere ... .
{4p62 ex rationis futurae praeterit praesentis}                     ... third form of knowledge (cognitio) ...  sub aeternitatis specie and  sub necessitatis specie mean the same ...
 ... under the form of eternity or necessity ...  sub ... aeternitatis seu  [mng-eqv] necessitatis specie
{5p23 Mens non absolute destrui}                                            ... something (aliquid) remains  ...  puzzling in context of {2p07}  ...
 ... The human mind cannot be absolutely destroyed with the body, but there remains of it something which is eternal ...  ... Mens humana non potest cum corpore absolute destrui sed ejus aliquid remanet quod aeternum est ... .
 ... .there is something ... .which is conceived  ... through the very essence of God  ... this  ... which appertains to the essence of the mind, will  ... be eternal ...  ...  In Deo  ...  datur conceptus seu [mng-eqv] idea quae corporis humani essentiam exprimit  ... quod ad essentiam mentis humanae pertinet  ... erit  ... aeternum ...
5p23s Nec tamen fieri potest ut recordemur nos ante corpus exstitisse    ... our memory cannot not be eternal since our body cannot have received imprints (traces, down here vestigia, elsewhere called affectiones, imagines) before it existed, yet "we feel" (sentimus) that our mind  (and "our mind" is the compound structure of ideas of all imprints of the body since it came into being) is eternal  ...  puzzling in context of {2p07}  ...
 ... This  ... expresses the essence of the body under the form of eternity, is, as we have said, a certain mode of thinking, which belongs to the essence of the mind, and is necessarily eternal.
Yet it is not possible that we should remember that we existed before our body, for our body can bear no trace of such existence, neither can eternity be defined in terms of time, or have any relation to time. But, notwithstanding, we feel and know that we are eternal. For the mind feels those things that it conceives by understanding, no less than those things that it remembers
 ... we do not remember that we existed before the body, yet we feel that our mind, in so far as it involves the essence of the body, under the form of eternity, is eternal, and that thus its existence cannot be defined in terms of time, or explained through duration. Thus our mind can only be said to endure, and its existence can only be defined by a fixed time, in so far as it involves the actual existence of the body. Thus far only has it the power of determining the existence of things by time, and conceiving them under the category of duration.
 ... haec  ... quae corporis essentiam sub specie aeternitatis exprimit, certus cogitandi modus qui ad mentis essentiam pertinet quique necessario aeternus est.
Nec tamen fieri potest ut recordemur nos ante corpus exstitisse quandoquidem nec in corpore ulla ejus vestigia dari nec aeternitas tempore definiri nec ullam ad tempus relationem habere potest. At nihilominus sentimus experimurque nos aeternos esse. Nam mens non minus res illas sentit quas intelligendo concipit quam quas in memoria habet
 ...  non recordemur nos ante corpus exstitisse, sentimus tamen mentem nostram quatenus corporis essentiam sub aeternitatis specie involvit, aeternam esse et hanc ejus existentiam tempore definiri sive per durationem explicari non posse. Mens igitur nostra eatenus tantum potest dici durare ejusque existentia certo tempore definiri potest quatenus actualem corporis existentiam involvit et eatenus tantum potentiam habet rerum existentiam  tempore determinandi easque sub duratione concipiendi
{5p29 mens intelligit corporis essentiam}                               ... third form of knowledge (cognitio) ... mind conceives the essence of body under the form of eternity ...
 ... Whatsoever the mind understands under the form of eternity, it does not understand by virtue of conceiving the present actual existence of the body, but by virtue of conceiving the essence of the body under the form of eternity.  ... Quicquid mens sub specie aeternitatis intelligit, id ex eo non intelligit quod corporis praesentem actualem existentiam concipit sed ex eo quod corporis essentiam concipere sub specie aeternitatis.
5p29s relatione ad certum tempus et locum existere vel quatenus ipsas in Deo   ... two ways to conceive things ...
 ... Things are conceived by us as actual in two ways; either as existing in relation to a given time and place, or as contained in God and following from the necessity of the divine nature. Whatsoever we conceive in this second way as true or real, we conceive under the form of eternity, and their ideas involve the eternal and infinite essence of God, as we showed in II. xlv. and note, which see. ..Res duobus modis a nobis ut actuales concipiuntur vel quatenus easdem cum relatione ad certum tempus et locum existere vel quatenus ipsas in Deo contineri et ex naturae divinae necessitate consequi concipimus. Quae autem hoc secundo modo ut verae seu reales concipiuntur, eas sub aeternitatis specie concipimus et earum ideae aeternam et infinitam Dei essentiam involvunt, ut propositione 45 partis II ostendimus, cujus etiam scholium vide.
{5p38 secundo tertio cognitionis minus mali minus timet}   ... eternal life for the mind (see above) but your imaginatio (cognitio primo genere) will not reach heaven ... the better your knowledge (2nd and 3rd kind) gets, the larger will be the part of your mind remaining ("remanet") in eternity ...
 ... In proportion as the mind understands more things by the second and third kind of knowledge ... less fear of death. PROPOSITIO XXXVIII: Quo plures res secundo et tertio cognitionis genere mens intelligit ... mortem minus timet
 ... The mind's essence consists in knowledge  ...  therefore, in proportion as the mind understands more things by the second and third kinds of knowledge, the greater will be the part of it that endures ...  ... Mentis essentia in cognitione consistit  ... quo igitur mens plures res cognoscit secundo et tertio cognitionis genere, eo major ejus pars remanet ...  

Equivalence claims involving aeternus, aeternitas
{1d06}[notes] 1. God 2. a being absolutely infinite-that is, a substance consisting in infinite attributes, of which each expresses eternal and infinite essentiality. 1. Deum 2. ens absolute infinitum hoc est substantiam constantem infinitisattributis quorum unumquodque aeternam et infinitam essentiam exprimit.
{1d08}[notes] 1. eternity 2. existence itself, in so far as it is conceived necessarily to follow solely from the definition of that which is eternal. 1. aeternitatem 2. ipsam existentiam quatenus ex sola rei aeternae definitione necessario sequi concipitur.
{1p19} 1. God 2. substance, which necessarily exists 3. [that of which] existence appertains to its nature 4. [that of which existence] follows from its definition 5. [that which] is eternal 1. Deus 2. substantia quae necessario existit 3. cujus naturam pertinetexistere 4. ex cujus definitione sequitur ipsum existere 5. est aeternus.
{1p21} 1. always exist and be infinite 2. are eternal and infinite 1. semper et infinita existere debuerunt 2. aeterna et infinita sunt.
{4p62} 1. under the guidance of reason 2.under the form of eternity 3. [under the form of ] necessity [De conceptioni]
1. ducente ratione 2. sub aeternitatis specie 3. [sub] necessitatis specie
{5p30} 1. Conceive things  under the form of eternity 2.  conceive things in so far as they are conceived through the essence of God as real entities 3. [conceive things] in so far as they involve existence through the essence of God 1. Res sub specie aeternitatis concipere 2. resconcipere quatenus per Dei essentiam ut entia realiaconcipiuntur 3. [resconcipere] quatenus per Dei essentiam involvunt existentiam