Spinoza's Ethics: II.P27: Adequate Ideas Are Not Based In Scientific Understanding

Spinoza is asserting that an idea can be adequate without understanding the object of the idea. For example, by touching a hot stove, an individual can have an adequate idea of the pain experienced by touching a hot surface. Adequate understanding does not include knowledge of nerves and their operation in transmitting information about temperature. His demonstration here is more generic but more widely applicable. Ideas can be adequate at a level of generalization of the interaction of component parts - of which there are infinite  - without understanding the component parts.

Idea cujuscunque affectionis corporis humani adæquatam ipsius humani corporis cognitionem non involvit.

Translated as,

The idea of whatsoever modification of the human body does not involve an adequate understanding of the human body itself.

DEMONSTRATIO: Quælibet idea cujuscunque affectionis humani corporis eatenus naturam corporis humani involvit quatenus ipsum humanum corpus certo quodam modo affici consideratur (vide propositionem 16 hujus). At quatenus corpus humanum individuum est quod multis aliis modis affici potest, ejus idea etc. Vide demonstrationem propositionis 25 hujus.

Translated as,

Anywhere the idea of whatsoever modification of the human body involves as such the nature of the human body insofar as the human body itself is considered to be affected in some certain way (see IIP16). But insofar as the human body is an individual because it is able to be affected by many other modes, the idea of it etc. See IIP25D.