Spinoza's Ethics: II.P18

Here in another area, that of memory, Spinoza reemphasizes that these ideas tell more about the nature of the human body than of the world around us. A contemporary example in my world is that investment results tell less about the investing world than they do about the investor. The critical variable is the knowledge of the subject - as a kind of emphatic support for Socrates' maxim "Know Yourself." Spinoza is arguing that fundamentally all attempts at knowledge move forward with increased data about self while focusing data-gathering on the world around. Memory simply amplifies this dynamic.

Si corpus humanum a duobus vel pluribus corporibus simul affectum fuerit semel, ubi mens postea eorum aliquod imaginabitur, statim et aliorum recordabitur.

Translated as,

If the human body has once been affected by two or more bodies at the same time, when the mind later imagines one of them, it will immediately recall the other of them.

DEMONSTRATIO: Mens (per corollarium præcedentis) corpus aliquod ea de causa imaginatur quia scilicet humanum corpus a corporis externi vestigiis eodem modo afficitur disponiturque ac affectum est cum quædam ejus partes ab ipso corpore externo fuerunt impulsæ sed (per hypothesin) corpus tum ita fuit dispositum ut mens duo simul corpora imaginaretur; ergo jam etiam duo simul imaginabitur atque mens ubi alterutrum imaginabitur, statim et alterius recordabitur. Q.E.D.

Translated as,

The mind (by IIP17C) imagines some body for this reason because, of course, if the human body is afflicted by traces of an external body in the same way as it is disposed and is affected when certain parts of it are pushed on by the external body itself but (by hypothesis) the body will be so disposed that the mind imagines the two bodies together; therefore now even will imagine the two simultaneously and the mind, when it imagines the one, will immediately imagine the other.

SCHOLIUM: Hinc clare intelligimus quid sit memoria. Est enim nihil aliud quam quædam concatenatio idearum naturam rerum quæ extra corpus humanum sunt involventium quæ in mente fit secundum ordinem et concatenationem affectionum corporis humani. Dico primo concatenationem esse illarum tantum idearum quæ naturam rerum quæ extra corpus humanum sunt, involvunt, non autem idearum quæ earundem rerum naturam explicant. Sunt enim revera (per propositionem 16 hujus) ideæ affectionum corporis humani quæ tam hujus quam corporum externorum naturam involvunt. Dico secundo hanc concatenationem fieri secundum ordinem et concatenationem affectionum corporis humani ut ipsam distinguerem a concatenatione idearum quæ fit secundum ordinem intellectus quo res per primas suas causas mens percipit et qui in omnibus hominibus idem est. Atque hinc porro clare intelligimus cur mens ex cogitatione unius rei statim in alterius rei cogitationem incidat quæ nullam cum priore habet similitudinem; ut exempli gratia ex cogitatione vocis pomi homo romanus statim in cogitationem fructus incidet qui nullam cum articulato illo sono habet similitudinem nec aliquid commune nisi quod ejusdem hominis corpus ab his duobus affectum sæpe fuit hoc est quod ipse homo sæpe vocem pomum audivit dum ipsum fructum videret et sic unusquisque ex una in aliam cogitationem incidet prout rerum imagines uniuscujusque consuetudo in corpore ordinavit. Nam miles exempli gratia visis in arena equi vestigiis statim ex cogitatione equi in cogitationem equitis et inde in cogitationem belli etc. incidet. At rusticus ex cogitatione equi in cogitationem aratri, agri etc. incidet et sic unusquisque prout rerum imagines consuevit hoc vel alio modo jungere et concatenare, ex una in hanc vel aliam incidet cogitationem.

Translated as,

From here we understand clearly what is memory. For there is nothing else than a certain connection of ideas involving the nature of things which are outside the human body that happen in the mind following the order and connection of the affections of the human body. I say first that connection is such of those ideas which involve the nature of things which are outside the body, moreover not of ideas which explain the nature of the same things. For they are actually (by IIP16) ideas of affections of the human body which involve just the nature of this [human body] more than the nature of the external bodies. I say next that this connection happens following the order and connection of the affections of the human body so that I might distinguish this from the connection of the ideas which happen following the order of the intellect by which things the mind perceives by their first causes and which is the same in all people. And here next we understand clearly why the mind from thinking of one thing immediately moves to the thought of another thing which has no commonality with the prior one; as for example from the thought of the name fruit a roman person immediately moves in thought to fruit which has no commonality with that articulated sound and nothing in common unless some body of the same man has been often affected by these two that is because the man often has heard the word "fruit" as long as he saw the fruit itself and thus each and everyone moves from one thought to another just as the images of things and the custom of each and everyone has ordered in the body. For the soldier, for example, by seeing the tracks of a horse in the arena moves immediately from the thought of a horse into the thought of cavalry and from there into the thought of war etc. But a farmer moves from the thought of a horse into plowing, land etc and so each and everyone just as the images of things he is accustomed to connect this or join in another way, moves from one into this or another thought.