An advertising truism is that there are three magic words, NEW, FREE, and SEX, and the greatest of these is ... (I think I need not complete this for you).

The age we live in is beginning to recognise how diverse sexual urges are, and accepting that human sexuality is more complex than has hitherto been understood.

We know things about ourselves that have to do with our 'urges' that nobody else knows, not even our nearest and dearest. Some of us may suspect that this hiddenness is not just true of us, but of every member of the human race.

Let us first establish what sex is for, and to do this we must look at one of the most neglected books, Genesis, the book of origins.

Nowadays there is a tendency to set up an Aunt Sally, to proclaim the Creation story of Genesis as disproved by science, and to dismiss it from all consideration.

This is such a shame, because its insights are unique, and desperately needed. If we do live in a universe in which biological life is just a chance rearrangement of chemicals, and there has never been anything other that a zillion other random events before now, and we are all going to a total extinction, with no purpose other than pleasure, then let us indeed eat drink and be merry, for tomorrow we die.

If you believe this is the sum of life, I cannot address you meaningfully. But if you think in your heart of hearts that what you know about humanity means that this materialist view does not explain everything, especially not your emotions, your perception of beauty, your sense of duty, and the strongest possible desires which seem to have no logic, you are at least asking the right questions.

The book of Genesis is trying to answer these questions. It is a sequence of books within a book. It is easy to spot this once you cotton on to the fact that the title of each mini-book comes at the end of it, not the beginning. We put titles at the beginning because we bind pages into a book. But when you have a scroll, pages stuck edge to edge in a continuous roll, the smart place to put the title is at the end, where you will see it first if you unroll an already read scroll.

All the titles in Genesis are in the form 'These are the generations of ...' to use the old-fashioned translation we are most used to. It comes out as 'This is the account of ...' in the more modern translation I am using here.

The first account is of 'the heavens and the earth', the second is of 'Adam's line', the third of Noah, and so on. The original Hebrew never had chapters and verses, for these were added in the middle ages to the then Latin translation. So the accounts actually end in the middle of a verse. But I am presenting the first two accounts without chapter and verse indications, so that their natural ending is clearer.

This is why there are overlaps. Adam's story mentions the birth of Seth, and then so does Noah's (Gen 4:25 and Gen 5:3-4), which also has the general statement that Adam had other sons and daughters not mentioned by name. It is as if each account was originally meant to be read on its own, and so key elements of the previous account are mentioned briefly at the beginning of the next. The first account can only have been given by revelation, but the later accounts may well have been family archives, oral or written we will never know.

The first account of origins is not a sequential, step by step, account, but a thematic story with the threefold cycle of light, then liquids and gases, finally solids, repeated. First without detail, then with more detail. The first and fourth segments deal with light as a force, and the sources of light. The second and fifth segments deal with the atmosphere and the oceans as entities, then their occupants. The third and sixth segments deal with solid earth, and then its occupants.

The word used for 'day' can mean any sort of division of time. The Greek word for story is 'myth'. Two pieces of etymology not to be overlooked.

With these introductory comments in mind, please now read the first account of our origins.

If the amount of detail given is any guide to the purpose of this story of origins, then the creation of humans is the climax and focus of the story, occupying about one fifth of the whole story. For this act of creation alone are ascribed purposes, duties, and promises.

The environmentalists are right. The most fundamental duty of the human race is defined here, as custodians of this planet and all that lives on it.

The planet is described as a unified design, with some living elements intended as the means of support for others. Each species is meant to interlock with the other species. The focus on design cannot be ignored, nor the verdict that everything made fitted into the plan (for what else can 'good' mean in this context?). And the method of reproduction is defined: seeds, reproducing 'according to their kinds'.

But in defining humans, the words 'let us make man in our image, in our likeness ... so God created man in his own image, in the image of God he created him; male and female he created them' are so emphatic. We are like God, we share His character, we are male and female.

We are not white and black, tall and short, strong and weak, fat and thin. We are male and female. This is the key piece of distinctiveness built into humanity. This is the big differentiator.

But both male and female are like God. God is both Father and Mother to us, whatever the linguistic habits are in various languages.

And because this is such a key concept the second story of origins focuses on the need of the man to have a 'suitable helper'.

If you want a key verse from this account, it must be: 'for this reason a man will leave his father and mother and be united to his wife, and they will become one flesh.'

Our sexuality as humans is the most important feature of our lives. The first commandment addressed to humans in the Bible is: 'Be fruitful and increase in number'. This is the urge that defines us, the urge to beget, the urge to conceive.

Before the first disobedience 'the man and his wife were both naked, and they felt no shame'.

After the first disobedience, 'then the eyes of both of them were opened, and they realised they were naked; so they sewed fig leaves together and made coverings for themselves'.

Even knowing they were naked was the indicator of that disobedience: 'who told you that you were naked? Have you eaten from the tree I commanded you not to eat from?'

What conclusions can we draw from this story? Many, no doubt, that there is no space for here. But this conclusion is safe: if there is any truth in this story, our sexuality is a hugely powerful force within us, by intention of our designer, and that departing from that design will cause us grief.

The western world, inasmuch as it is trying to deny the distinctiveness of male and female, and is trying to take away marriage and the family as the bedrock of society, is denying the very foundations of the human race's place in the designer's plan.

Individually we are responsible for the way we respond to this trend. Do we follow fashion, or challenge it?

Most of our desires are very logical and rational. Often they are simply a response to what our bodies need, in terms of food, water, and warmth. Our emotional needs of security, freedom from fear, the good opinion of others, explain a great many more. But there are two areas of desire that are less easy to understand: the craving that drug addiction brings, and the urges for sexual fulfilment.

I have nothing to say about the craving drug addicts suffer from. I smoked as a youth (in the 1950s when little was publicly known of the dangers) and gave up permanently at the age of 21. So that sort of craving is a distant memory now. I have no idea what other drug cravings might be like, and no intention of finding out.

But like every other human (I suppose) I know what sort of urges there are in my body, and what triggers them. I know why people will do things (especially if they believe they are unobserved) that they later feel a great degree of shame about.

And if any one is curious to know, one's urges do not seem to diminish with age in one's sixties, and if you wait ten years I will answer for the seventies too, if I am spared that long.

In the animal kingdom the sexual urges observable all seem to focus on a single objective: procreation. The male copulates with the female when the female is in her short period of fertility, and only then. This is true whether the fertilisation of the eggs is internal or external, whether penetration is required or not. Whatever urges they have built into them, the procreative urge is a tremendously powerful force.

With humans everything is much more complicated, not least because we seem to adopt the view that sex is mainly for pleasure, and pregnancy something akin to a disease. The Internet itself has more commercial activity associated with satisfying the 'sex for pleasure' urge than any other single commercial sector. It is streets ahead of Internet share trading (the desire for wealth?), which comes a very poor second.

All this would be a little easier to understand if it was always pointing in the direction of finding a desirable mate for the ultimate purpose of procreation. We are more complex than the animal kingdom in a host of other ways besides how we experience sexual urges.

But what can one say about sexual urges that deviate from this obvious goal of the begetting and conceiving of babies? What word even dare one use? Is 'deviate' acceptable? (It comes from Latin words meaning straying from the path) Dare I call attractions which cannot possible lead to procreation deviations? This may sound judgmental, arrogant, and certainly would be condemned by the proponents of political correctness.

Here the human race seems unique in all creation, that men and women seek to respond to urges that cannot possibly be explained by any fundamental instinct to procreate. Where do these urges come from?

The Bible mentions the two most obvious ones in Leviticus (of at least three thousand years ago), so there is nothing recent about this. The passage begins with the condemnation of incestual relationships, and we know there are good medical reasons for following these moral imperatives. And then other forbidden territory is defined:

It should be interesting to measure your own reactions on reading this. You might be distracted by the reference to sexual activity during menstruation, and wonder who Moloch was (the god of a neighbouring tribe, actually), but I suggest you set aside those thoughts. The condemnation of homosexuality and bestiality is even clearer in the next but one chapter, if you are in any doubt.

It seems that God is perfectly aware the we humans can get it all wrong, and misdirect our sexual energies. In the nation he chose to be a living example of his design for humans, God wanted total purity, and set drastic sanctions. Leave aside the sanctions, for no one advocates them for today. But can we ignore the standards? Can we find true happiness in a path away from the designer's intentions?

But there can be deep friendships between two men, and two women, and these friendships can take on an importance in the lives of those involved as significant as any other bond between two humans.

When we read the words that King David spoke at the death of Jonathan, eldest son of King Saul, at the hands of the Philistines, once again the Bible becomes a reference point on a difficult topic:

How the mighty have fallen in battle!
Jonathan lies slain on your heights.
I grieve for you, Jonathan, my brother;
You were very dear to me.
Your love for me was wonderful,
More wonderful than that of women.
How the might have fallen!
The weapons of war have perished!

Each of us finds attraction in our own individual way. The only safe rule is that we treat sexual urges as an opportunity to give, rather than take. Those who exploit others, whether naturally or unnaturally, are dehumanising themselves, and cutting themselves off from any hope of real happiness.