To Will One Thing

A prayer from Purity of Heart Is to Will One Thing by Søren Kierkegaard.

Father in Heaven, what are we without you?
What is all that we know, vast accumulation though it be,
But a chipped fragment if we do not know you?
What is all our striving?
Could it ever encompass a world,
But a half-finished work
If we do not know you?
You, the One who is one thing and who is all. 

So may you give
To the intellect, wisdom to comprehend that one thing
To the heart, sincerity to receive this and this only
To the will, purity that wills only one thing
In prosperity, may you grant perseverance to will one thing
Amid distraction, collectedness to will one thing
In suffering, patience to will one thing. 

You that gives both the beginning and the completion
May you early, at the dawn of the day,
Give to the young the resolution to will one thing
As the day wanes, may you give to the old
A renewed remembrance of that first resolution
That the first may be like the last
And the last like the first
In possession of a life that has willed only one thing,
To know God.

One bible study writer notes that:

Purity of heart comes from being drawn to God, and grappling in his presence with our tendencies to sin—to cover, prevaricate, and numb who we really are from ourselves, from God, and from others. ... 

Deceit, or impurity of heart, is what we do when we will two things, rather than one. We do one thing and want people to believe we do another. We feel one thing and want people to think we feel another. Psychologists tell us a divided heart is highly correlated with addiction, depression, violence, aggression, suicide, eating disorders, self-medication, and all manner of human dis-ease.

And in a discussion of one of the Beatitudes ("Blessed are the clean of heart, for they will see God." — Matthew 5:8), another notes that Rene Girard theorizes that our inability to desire 'one thing' is a result of learning to desire from others:

We want what we want because we have witnessed important people in our lives wanting those things. Many of us have witnessed toddlers, surrounded with toys, fighting over just one of them because one toddler has made it look more desirable than all the other toys. 

Once we realize the importance of what others desire, and join them in pursuit of what is desired, we can swiftly move from being close allies to archrivals. We compete with them to obtain what they modeled for us as desirable. When it becomes impossible for both of us to have whatever it is we desire, our rivalry can turn murderous.

The solution (emphasis mine):

We learn [to will one thing] by truly embracing Jesus Christ and his mission to offer a real foretaste of the kingdom of heaven to those most in need of its blessings. The antidote to desires that take our attention away from the kingdom of heaven is compassion — the desire to make the love of God tangible to those who can only look to God for their needs.

See also Be Whole-Hearted by Cynthia Bourgeault.