"The spirit is willing, but the body is weak." (Matthew 26:40-41)

Then he returned to his disciples and found them sleeping. "Couldn't you men keep watch with me for one hour?" he asked Peter. "Watch and pray so that you will not fall into temptation. The spirit is willing, but the flesh is weak." (Matthew 26:40-41)

Why did Jesus say this?

Jesus said this to Peter, James and John after his first prayer at Gethsemane.

Jesus was making two important points here. The first is that his disciples had not followed his instruction. Jesus had requested that Peter, John and James keep watch, as he was expecting to be arrested shortly:
"Stay here and keep watch with me." (Matthew 26:38)
In the first part of Matthew 26:40 above, Jesus is chastising some of his disciples for not following his instructions to watch out for him while he prayed.

The second part of this statement indicates a core element of Jesus' teachings. Jesus clearly taught the  distinction between the spiritual person (soul or spirit-person) and the physical body:

What does 'the spirit is willing' mean?

Who is Jesus referring to as the "spirit"? We can see here that the "spirit" has a will - "is willing." Only a person can have a will, and thus we can conclude that the "spirit" Jesus refers to is the person within.

The word "spirit" is being translated from the Greek word πνεῦμα (pneuma). According to the lexicon, this means, "the vital principal by which the body is animated." as well as "a life giving spirit," and "the soul."

Many refer to the soul as a part of a person - like an organ or something. Others will refer to the soul as one's morality.

Here we can see that Jesus' use of the word "spirit" does not relate to a part of a person or one's morality. Jesus is referring to "spirit" as the individual spiritual person: Again, only an individual person (spirit) can have a will.

This all means that Jesus' statement is suggesting that his spirit-person within can make a determination. But within the physical world, there are other factors to contend with.

What does 'the body is weak' mean?

The verse states Jesus said, "but the body is weak." This is a slight mistranslation because the Greek word being translated to "body" is σάρξ (sarx) means "flesh (the soft substance of the living body, which covers the bones and is permeated with blood) of both man and beasts." Without the parenthesis: "flesh of both man and beasts."

More importantly, the word also means, again according to the lexicon, "the sensuous nature of man, "the animal nature"" and "the animal nature with cravings which incite to sin."

We can see from these definitions that the word "body" falls short of capturing the real meaning of Jesus' statement. He was saying that while the spiritual person might be willing to do something, the animal-type cravings inherent in the physical body can pull the person to act otherwise.

Why is the body 'weak'?

How can we be willing to do something, yet be driven to do something else by virtue of our physical body and its inherent "cravings"? Many characterize this as "the devil," as in: "the devil made me do it." This is often conjured as having a little devil on our shoulders, who is constantly tempting us.

The answer lies within the reason for our occupation of a physical body in the first place.

Each of us is a spirit-person created by the Supreme Being to share the spiritual realm with Him as one of His caregivers. He wanted to share loving relationships with us. But real love requires freedom, so God gave us the freedom to love Him or not. He gave us the choice to engage in a relationship with Him or not.

Exercising that choice means that we need to be presented with the opportunity to choose otherwise. Without the choice to choose otherwise, we would not have the freedom to choose to engage in our relationship with God.

The physical world offers us the opportunities to choose otherwise in a myriad of different ways. Here we get to follow God or deny God. Here we get to help others or harm others. Here we get to chase self-centered dreams or try to help those who are less fortunate.

We have this myriad of choices in order to not only choose, but also to learn. This world of choice was also designed to help us grow and evolve through the consequences of our behavior.

This is why, for example, those who commit illegal acts will typically pay the price through jail or otherwise. And for those who get away with their crimes, their consequences will come later, likely in the next life.

This also explains why some children are born into starvation or other challenging situations. They may be suffering the consequences for the activities of a previous lifetime.

To graduate from this world of choice and consequence means to evolve to a point where we are ready to assume our innate spiritual nature in the spiritual realm. The highest realm of the spiritual world is full of love without self-centeredness.

But those of us who are still dealing with self-centeredness are relocated by taking on physical bodies within the physical world, a virtual world where we take on a new identity with every incarnation.

Since we are spiritual by nature, relocation requires a virtual existence. One where we could take on a role different than our real nature. In order to take on a self-centered existence, we need a virtual personality - because our true nature is loving and selfless.

So the Supreme Being designed a virtual universe where we could occupy temporary physical bodies and play temporary roles, in order to exercise our freedom of choice and our self-centeredness, and learn lessons through consequences.

We might compare this to a play, where the actors put on costumes and play roles different than their "real" roles.

To complete the analogy, our "costumes" are these physical bodies.

We know these physical bodies are temporary and we are playing temporary roles in them because our bodies keep changing and our roles keep changing - yet each of us is still the same person within. When our body is young, we play the role of a child. When our body grows older, we play the role of a teenager. Later we play the role of an adult, with a job and family. Then later we play the role of a senior citizen.

Each of us is distinct from the roles we play in the physical world. These roles are required by the society and culture of the physical world. 

This doesn't mean that we have to identify with these roles, however. We can know that when our physical body dies, our roles in this world will die with it.

Why does the body not satisfy us?

The physical body is a temporary vehicle for the living being. Each of us is driving our physical body much like a person would drive a car. And as most of us have experienced, when we are driving a car we begin to identify with it.

We also begin to identify the other drivers on the road with their cars. When we are passed on the highway by a speeder in a red car, we will say, "that red car is speeding." We are thus identifying the driver as their car.

In the same way, after a short time within these physical bodies, we begin to identify with them. This is the design of the physical world, as programmed by the Supreme Being.

As we identify with these physical bodies, we also seek our happiness through them. We begin to think that our happiness revolves around whether the body feels good. This is also designed by the Supreme Being.

The body is designed to release neurotransmitters called dopamine, serotonin and endorphins, which signal to our brain that something is good for the body. Eating something sweet or having a sexual orgasm, for example, will cause the brain to release these "feel good" chemicals. These "feel good" chemicals trick us - the spirit-person within - into thinking we become happy when the nerves are saturated with one or more of these "feel good" neurotransmitters.

Yet no one actually becomes happier when the body is saturated with these neurotransmitters. The sensation might feel good to our body, but the spiritual person within is not satisfied.

This might be likened to a car driver feeling hungry and thinking that if he filled his car's tank with gas the driver would not feel hungry anymore. No. The car's gas tank gets filled up, but the driver's stomach is not touched by the gas. The driver will still feel hungry, even when the gas tank is full.

It is the same with the spirit-person driving the physical body. The reason that so many people living in the physical world are unhappy - even those with great wealth and all the sweet foods and sexual organisms they could ever want - is because we are spiritual in essence, not physical.

And this is what Jesus is trying to teach his students. His students' bodies may feel more comfortable sleeping, but their spirit-persons will only be satisfied when they are fixed within their real identity - being one of the Supreme Being's loving servants.

The Supreme Being wants us back. He wants us to return to His loving arms. This is why Jesus' most important teaching was:
"'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment." (Matt. 22:37-38)