The origin of the IMF is one of the most debated issues in astrophysics. Francesco introduced me to this fascinating topic in 1989 at an IAU colloquium in Granada. I will discuss new insights into this problem since the IMF@50 conference coming from Herschel observations. The Herschel results point to the key role of the quasi-universal filamentary structure pervading molecular clouds. They suggest that the prestellar cores responsible for the IMF peak result from gravitational fragmentation of filaments near the critical line mass.