It is, perhaps, a strange lesson from a pope: Even the erotic can be divine.

That is one take-away from the landmark document by Pope Francis on family life, a work that translates in English as "The Joy of Love." Married couples, the pope says, should not fear “a healthy sexual desire.” In fact, this pope-turned-marriage counselor suggests, why not start your days with a morning kiss?

He goes on to offer other secrets to a happy, healthy home in a document praised by some but derisively dubbed “The Joy of Sex” in at least one conservative blog.

“In no way, then, can we consider the erotic dimension of love simply as a permissible evil or a burden to be tolerated for the good of the family,” the often-surprising pontiff writes. “Rather, it must be seen as gift from God that enriches the relationship of the spouses.”

He gives a blunt “no” to gay marriage, and warns his flock not to forget the “differences between sexes.”

Yet while men may be men, and women may be women, there are little tricks to cohabiting peacefully as husband and wife. Spouses should consider waiting “at the door” when the other returns home. Both husband and wife should do housework.

But yes, he concedes, sometimes the spark does go out of a relationship. Yet, he teaches, that doesn’t have to mean the end. What is left, he says, can be a deep-seated sense of partnership and love that is no less valuable.

“There is no guarantee that we will feel the same way all through life,” the pope writes. “Yet if a couple can come up with a shared and lasting life project, they can love one another and live as one until death do them part, enjoying an enriching intimacy."

He goes off on “safe sex” as a poor excuse for sex before marriage, but never bluntly denounces the use of artificial birth control. He encourages sexual education of children. But he is still the pope and says such teachings should be directed largely at the promotion of modesty.

“It is always irresponsible to invite adolescents to toy with their bodies and their desires, as if they possessed the maturity, values, mutual commitment and goals proper to marriage,” he writes. “They end up being blithely encouraged to use other persons as a means of fulfilling their needs or limitations.”