His gloomy and unhappily subtle mind cannot bear the light which Grotius presents to him.

The embroiled ideas and distinctions of his Peripatetic philosophy form round him a thick cloud impenetrable by the strongest rays of truth.

This is Barbeyrac's judgment of him.

Felde met with some partisans of Grotius who confuted him: Theodorus Graswinckel, Advocate, his relation and friend, undertook his defence; and the redoubled efforts of the Helmsted Professor did not lessen his book in the esteem of the public.

Not that the work is perfect; this, his admirers and those who were most disposed to do him justice, frankly own.
His general principles touching natural law are very solid; but they are too intricate, and it requires deep meditation to unfold them.