Marriage is an institution as old as the human race itself. It started in the Garden of Eden with our first parents. God blessed Adam and Eve: "Increase and multiply and fill the earth" (Gen. 1:28); and God's fundamental laws with regard to marriage are well expressed by Adam: "Wherefore, a man shall leave father and mother, and shall cleave to his wife: and they shall be two in one flesh" (Gen. 2:24).

Thus, marriage can be defined as a life long union between a man and a woman who are lawfully capable of giving irrevocably to each other the right to acts necessary for the generation and education of children, mutually obliging themselves to a common way of life in order to work out their eternal salvation. Among the baptized, every true marriage is, in itself and by itself, a sacrament instituted by Christ to produce grace.

The most essential factor in marriage, of course, is the contract. A contract is an agreement between two parties, each assenting to give something to the other or to do something for the other for a definite length of time. There cannot be a contract without the free consent of both parties.

There are six obstacles to consent.

1. Lack of the use of reason, infants, the seriously mentally ill, the intoxicated, the drugged, the hypnotized cannot give true consent.

2. Defective knowledge. In order to give consent, the person must know the essentials-that marriage is a permanent union of a man and a woman for the purpose of procreating children. He must know that this requires bodily cooperation of husband and wife. After puberty, it is presumed that the person knows these basic facts. It is not necessary that he know all the biological mechanisms involved in the sex act, conception, pregnancy and birth.

3. Mistaken identity. If you "marry" one person but thought that you were marrying another (his twin, for example) there is no true consent.

4. Pretense. People who say "I will" while acting out a marriage on the stage or in a movie are, of course, not married. There is no intention of getting married and, hence, no true consent. But if a person is a bride or groom in a real wedding ceremony, his external consent by saying "I will" is taken as evidence of true internal consent. He would have great difficulty trying to prove later that he said "I will" but did not really mean it.

5. Force or fear. Canon Law is specific on this matter, saying that "invalid is a marriage entered into through force or grave fear unjustly inspired from without, such that in order to escape from it, a party is compelled to choose marriage. No other fear, even if it furnish the cause for the contract, entails the nullity of marriage" (Canon 1087).

6. Intention contrary to the essence of marriage. If one or both parties would deny that marriage really is a contract binding on both parties, or that marriage gives the right to sexual intercourse, the marriage would be invalid, because denial would indicate a failure to under stand what marriage really is. You certainly are not making a contract when you do not believe there is a contract. And you are not making a contract involving sexual intercourse as one of the things promised if you do not believe that sexual intercourse is one of the things promised. But, as we have defined, marriage is a contract involving promise of sexual intercourse.

A Christian marriage must overcome all of these obstacles or it will not be a marriage.