Spinoza is removing the structure which supports the anthropomorphic
notion that God makes plans and then executes them. God expresses
through maximal power and in the expression of this power modal changes
occur. These modal changes occur within a causal chain limited by the
power of the attribute. Since modal change is causal simultaneously
(although expression may manifest non simultaneously) within different
attributes, we may have an impression of an idea through an object, but
that impression is not the power of expression of extending, but the power of expression of thinking. The power of expression
must occur only within the attribute.
Cujuscunque attributi modi Deum quatenus tantum sub illo attributo cujus modi sunt et non quatenus sub ullo alio consideratur, pro causa habent.
Translated as,
The modes of whatsoever attribute have God as cause insofar as it [God] is considered only under that attribute of which they are modes and not insofar as under any other [attribute].
Demonstratio: Unumquodque enim attributum per se absque alio concipitur (per propositionem 10 partis I). Quare uniuscujusque attributi modi conceptum sui attributi, non autem alterius involvunt adeoque (per axioma 4 partis I) Deum quatenus tantum sub illo attributo cujus modi sunt et non quatenus sub ullo alio consideratur, pro causa habent. Q.E.D.
Translated as,
For each and every attribute is conceived through itself and away from another (by IP10). For that reason the modes of each and every attribute have the concept of their own attribute as cause, moreover they [the modes] do not involve [the attribute] of another to the extent (by IPA4) that they have God as cause insofar as it [God] is considered only under that attribute of which they are modes and not insofar as under any other attribute.
Corollarium: Hinc sequitur quod esse formale rerum quæ modi non sunt cogitandi, non sequitur ideo ex divina natura quia res prius cognovit sed eodem modo eademque necessitate res ideatæ ex suis attributis consequuntur et concluduntur ac ideas ex attributo cogitationis consequi ostendimus.
Translated as,
Here it follows that the formal essence of things which are not thinking modes, does not follow so much from divine nature because it [divine nature] has known the things before but in the same mode and by the same necessity that the things ideated follow and are concluded from their own attributes as we show that the ideas follow from the attribute of thinking.