to appoint to an office or function; make or create: He was constituted treasurer. to establish (laws, an institution, etc.). ... to create or be tantamount to: Imports constitute a challenge to local goods.

Has constituted meaning?

: to make up or form something. : to be the same as something : to be equivalent to something. : to establish or create (an organization, a government, etc.)

What does so constituted mean?

The "so constituted" is referencing those who have not lost the urge to learn, in order to make his point. Hope this clears it up; thanks!