Pope Francis has described abortion as a "white gloves" equivalent of the eugenics programmes of the Nazi regime in the last century.
In a speech in Rome to the Family Forum on the 25th anniversary of that organisation, he described being "stunned" as a child when he learned what the Spartans did to a child born with malformations.
"They took him to the mountain and threw him down, to treat 'the purity of the race'."
Pope Francis said: "It was an atrocity. Today we do the same. Have you wondered why you do not see so many dwarves on the street? Because the protocol of many doctors – many, not all – is to ask the question: 'Is it malformed?' I say this with pain.
"In the last century the whole world was scandalised by what the Nazis did to treat the purity of the race. Today we do the same, but with white gloves."
His remarks on eugenics were delivered as an aside, but inserted in the main text published on the Vatican website.
The main thrust of the address was the holiness of marriage and family life. It comes a few weeks before he goes to Ireland, which has recently voted to liberalise its abortion laws, for the World Meeting of Families.
Pope Francis, possibly indicating some of his main areas of concern in the run-up to the meeting, said there is there is a need for a catechumenate for marriage, as there is a catechumenate for baptism.
Describing love as like "making pasta", he said: "Family life: it is a sacrifice, but a good sacrifice. Love is like making pasta: every day. Love in marriage is a challenge for men and women. What is the greatest challenge of man? Make more woman his wife. More woman. That grows as a woman. And what is the woman's challenge? Make your husband more man. And so they both go forward. They go forward."
There are three phrases that are magic but important in marriage, he continued. "First of all, 'leave': do not be intrusive with each other. 'Can I?' Show that respect for each other. Second: "Sorry". Apologising is something that is so important, it's so important! Everyone can be wrong in life, everyone. 'Excuse me, I did this ... Sorry, I forgot ...' And this helps keep going. Helps to carry on the family, the ability to apologise. It's true, apologising always involves a bit 'of shame, but it is a holy shame! 'Excuse me, I forgot ...' It's something that helps a lot to keep going. And the third: 'Thank you'. To have the greatness of heart always to say thank you."
He also praised the "holiness" of women who forgive their unfaithful husbands.
Pope Francis said: "Another thing that helps a lot of married life is patience: knowing how to wait. Wait. There are situations of crisis in life – strong crises, bad crises – where perhaps even times of infidelity come. When the problem can not be solved at that moment, it takes that patience of waiting, waiting. So many women – because this is more of the woman than of the man, but also the man sometimes does it – so many women in silence have waited, looking away, waiting for the husband to return to fidelity. And this is holiness. The holiness that forgives everything, because it loves. Patience. Much patience, one of the other. If one is nervous and cries, do not answer with another cry ... Be quiet, let the storm pass, and then, at the right moment, talk about it."