/summa/SS/SSI/SS_Q14:
We must now consider in particular blasphemy against the Holy Ghost: under which head there are four points of inquiry:
(1) Whether blasphemy or the sin against the Holy Ghost is the same as the sin committed through certain malice?
(2) Of the species of this sin;
(3) Whether it can be forgiven?
(4) Whether it is possible to begin by sinning against the Holy Ghost before committing other sins?