Illiterate hero will learn spells directly from deity

... instead of receiving a spellbook.

src/pray.c

@@ -1201,10 +1201,17 @@ pleased(aligntyp g_align)
                 }
                 otmp->otyp = rnd_class(g.bases[SPBOOK_CLASS], SPE_BLANK_PAPER);
             }
-            bless(otmp);
-            at_your_feet("A spellbook");
-            place_object(otmp, u.ux, u.uy);
-            newsym(u.ux, u.uy);
+            if (!u.uconduct.literate && !known_spell(otmp->otyp)) {
+                if (force_learn_spell(otmp->otyp))
+                    pline("Divine knowledge of %s fills your mind!",
+                          OBJ_NAME(objects[otmp->otyp]));
+                obfree(otmp, (struct obj *) 0);
+            } else {
+                bless(otmp);
+                at_your_feet("A spellbook");
+                place_object(otmp, u.ux, u.uy);
+                newsym(u.ux, u.uy);
+            }
             break;
         }
         default:

src/spell.c

@@ -1947,4 +1947,27 @@ spell_idx(short otyp)
     return -1;
 }
 
+/* forcibly learn spell otyp, if possible */
+boolean
+force_learn_spell(short otyp)
+{
+    int i;
+
+    if (known_spell(otyp))
+        return FALSE;
+
+    for (i = 0; i < MAXSPELL; i++)
+        if (spellid(i) == NO_SPELL)
+            break;
+    if (i == MAXSPELL)
+        impossible("Too many spells memorized");
+    else {
+        g.spl_book[i].sp_id = otyp;
+        g.spl_book[i].sp_lev = objects[otyp].oc_level;
+        incrnknow(i, 1);
+        return TRUE;
+    }
+    return FALSE;
+}
+
 /*spell.c*/