Full Idea
By 'mode' I understand the affections [affectiones] of substance, or that which is in another thing through which also it is conceived.
Gist of Idea
A 'mode' is an aspect of a substance, and conceived through that substance
Source
Baruch de Spinoza (The Ethics [1675], I Def 5)
Book Reference
Spinoza,Benedict de: 'Ethics', ed/tr. White,WH/Stirling,AH [Wordsworth 2001], p.3
A Reaction
The attributes actually make up the essential consitution of the thing, and then the modes are entirely dependent on that essence. This is thoroughly Aristotelian, even though 'substantial forms' had been given up by this date.
Related Idea
Idea 17170 An 'attribute' is what the intellect takes as constituting an essence [Spinoza]