Jim Carrey has learned to love — from an autistic child.

The 'Ace Ventura' star believes the son of his girlfriend Jenny McCarthy taught him the true meaning of love.

Carrey and McCarthy were amongst the protesters who marched in Washington DC on Wednesday to make people aware of toxins that are present in vaccines.

The actress claims that her five-year-old son, Evan, developed autism as a result of vaccine toxicity.

"He taught me how to love," Carrey told People magazine at the march.

"And without Evan I might never have seen the greatness of Jenny's spirit.

"(Jenny is) the source of all that is good (in my life)."