There he took his degree as doctor of law in 1818 , and as doctor of philosophy on 21 June 1821 .
In 1817 Da Costa went to Leyden , where he again saw much of Bilderdijk .
There Da Costa took Da Costa 's degree as doctor of law in 1818 , and as doctor of philosophy on 21 June 1821 .
In 1817 Da Costa went to Leyden , where he again saw much of Bilderdijk .