Pope Benedict published his first encyclical today in which he claimed that erotic love between a man and a woman risked being reduced to a "commodity" of sex if it was not part of a higher spiritual love.
"Deus Caritas Est" (God is Love), a highly professorial and academic 72-page treatise, sounded a keynote for Benedict's nine-month-old papacy by discussing God's love for man, man's love for God and love between humans.
"Today, the term 'love' has become one of the most frequently used and misused of words, a word to which we attach quite different meanings," the German-born pontiff said at the start of the encyclical, the highest form of papal writing.
"I wish in my first encyclical to speak of the love which God lavishes upon us and which we in turn must share with others," he wrote.
He said that while he discusses "the multiplicity of the meanings of love", one that stands out as needing clarification today is the "love between a man and a woman where body and soul are inseparably joined and human beings glimpse an apparently irresistible promise of happiness."
Much of the first half is dedicated to the relationship between "eros", or erotic love, and "agape", the Greek word referring to unconditional, spiritual and selfless love as described in Scriptures.
He speaks of "an intoxicated and undisciplined eros" which does not lead to God but to human degradation unless it is "purified" to provide much more than "just fleeting pleasure".
"Man is truly himself when his body and soul are intimately united; the challenge of eros can be said to be truly overcome when this unification is achieved," he writes.
The Pope acknowledges that in the past the "Church, with all her commandments and prohibitions" was seen as having been "opposed to the body." But he warns that contemporary society's way of exalting the body at all costs was deceptive and dangerous.
"Eros, reduced to pure 'sex', has become a commodity, a mere 'thing' to be bought and sold, or rather, man himself becomes a commodity," he said.
In the encyclical, the Pope defines 'eros' as "worldly love" and 'agape' as "love grounded in and shaped by faith" and says they can never be completely separated.
"The more the two, in their different aspects, find a proper unity in the one reality of love, the more the true nature of love in general is realised," he writes.
Before the encyclical was released Church leaders said they hoped it would help clarify the Catholic stand on erotic love properly understood in the context of a greater spiritual love.
"In our culture we presuppose that there must be a separation between eros - understood as human desire, sexually expressed - and agape," Cardinal Francis George of Chicago told a Vatican conference this week.
"The Pope tries to overcome, and I think does so successfully, a separation between eros and agape by pointing to the inner movement of erotic love toward a generosity between a man and a woman based on the total self-giving of one to the other for the sake of the other," George said.
The second part of the encyclical is dedicated to charity and charitable works as an extension of God's love for humanity.