Spinoza's Ethics: III.P17

Si rem quæ nos tristitiæ affectu afficere solet, aliquid habere imaginamur simile alteri quæ nos æque magno lætitiæ affectu solet afficere, eandem odio habebimus et simul amabimus.

If a thing which is accustomed to affect us with the affect of sadness, we imagine something to have similar of the other which is accustomed to affect us equally with a great affect of joy, we will have hatred for the same and we will love at the same time.

DEMONSTRATIO: Est enim (per hypothesin) hæc res per se tristitiæ causa et (per scholium propositionis 13 hujus) quatenus eandem hoc affectu imaginamur, eandem odio habemus et quatenus præterea aliquid habere imaginamur simile alteri quæ nos æque magno lætitiæ affectu afficere solet, æque magno lætitiæ conamine amabimus (per propositionem præcedentem) atque adeo eandem odio habebimus et simul amabimus. Q.E.D.

For it is (by hypothesis) this thing by itself the cause of sadness and (by IIIP13S) insofar we imagine the same with this affect, we have hatred of the same and insofar as besides we imagine something to have similar to another thing which is accustomed to affect us with a great affect of joy, equally with great spirit of joy we will love (by IIIP16) and to such a degree we will have hatred and at the same time love.

SCHOLIUM: Hæc mentis constitutio quæ scilicet ex duobus contrariis affectibus oritur, animi vocatur fluctuatio, quæ proinde affectum respicit ut dubitatio imaginationem (vide scholium propositionis 44 partis II) nec animi fluctuatio et dubitatio inter se differunt nisi secundum majus et minus. Sed notandum me in propositione præcedenti has animi fluctuationes ex causis deduxisse quæ per se unius et per accidens alterius affectus sunt causa; quod ideo feci quia sic facilius ex præcedentibus deduci poterant; at non quod negem animi fluctuationes plerumque oriri ab objecto quod utriusque affectus sit efficiens causa. Nam corpus humanum (per postulatum 1 partis II) ex plurimis diversæ naturæ individuis componitur atque adeo (per axioma 1 post lemma 3, quod vide post propositionem 13 partis II) ab uno eodemque corpore plurimis diversisque modis potest affici et contra quia una eademque res multis modis potest affici, multis ergo etiam diversisque modis unam eandemque corporis partem afficere poterit. Ex quibus facile concipere possumus unum idemque objectum posse esse causam multorum contrariorumque affectuum.

This constitution of the mind which of course from two contrary affects arises, is called vacillation of the mind, which hence sees the affect as doubt to the imagination (see IIP44S) and fluctuation of the mind and doubt are not different among themselves except following greater or lesser. But it ought to be noted that I in the prior proposition these fluctuations of the mind have followed from causes which by itself at times and and by accident at times are the cause of the affect; which thus I have made because so much more easily they are able to be deduced from the preceding; but not which I deny that the fluctuations of the mind and more arise from the object which might be the efficient cause of another affect. For the human body (by II Post.1) from more individual things of diverse nature is composed and to such a degree (by Axiom 1 after Lemma 3, see IIP13) from one and the same body is able to be affect in more and diverse ways and in contrast because one and the same thing is able to be affected by many ways, therefore also by many and diverse ways one and the same part of the body is able to be affected. From which we are able to easily conceive that one and the same object is able to cause of multiple and contrary affects.