Karma is a kind of memory.
We usually think of memory as pictures. A birthday, a face, a street we once lived on. But most memory has no pictures in it. The body remembers how to ride a bicycle years after the last ride. The tongue remembers how to shape a name. The stomach remembers a meal that once made it sick and turns at the smell of it. A player shoots a thousand free throws, and one day her arm knows the shot better than she does. She can feel whether the ball will drop before it reaches the rim.
Every deed done with wanting is written into us somewhere. That writing is the mark every deed leaves. The next time a like moment comes, the mark pulls us to do the same thing again. It is why a good habit is hard to begin and easy to keep, and a bad one easy to begin and hard to break.
So karma moves in a circle. A deed leaves a mark. The mark becomes a pull. The pull produces the next deed, and the next deed deepens the mark. Round it goes. A circle has no natural end. Something must break it.
There is a plain picture of this in almost every town. Where two sidewalks meet at a corner of grass, you will often find a thin brown line cut across the corner. No one laid that path. One person in a hurry cut the corner, then another, then a hundred. Now the grass will not grow there, and people walk the line without a thought. They are not choosing it. The path chooses for them.
Students of the brain say something like this in their own language. Cells that fire together wire together. Each time a thing is done, the connection that does it grows a little stronger. The path wears a little deeper.
Guru Nanak said it with paper and ink.
ਕਰਣੀ ਕਾਗਦੁ ਮਨੁ ਮਸਵਾਣੀ ਬੁਰਾ ਭਲਾ ਦੁਇ ਲੇਖ ਪਏ ॥
karaṇī kāgad man masavāṇī burā bhalā dui lekh pae |
Our deeds are the paper, and the mind is the inkpot. The bad and the good are both written down.
ਜਿਉ ਜਿਉ ਕਿਰਤੁ ਚਲਾਏ ਤਿਉ ਚਲੀਐ ਤਉ ਗੁਣ ਨਾਹੀ ਅੰਤੁ ਹਰੇ ॥੧॥
jiu jiu kirat chalāe tiu chalīai tau guṇ nāhī ant hare |1|
Wherever the push of our past deeds drives us, that is where we go. Your goodness, O Lord, has no end.
Guru Nanak, Raag Maru, Ang 990
The word in the second line is kirat. It means the push of all that we have done, the weight of the past leaning on the present. Kirat is not a single mark. It is all the marks together, pressing in one direction, the way many small streams make one current. Wherever it drives us, we go.
That would be a grim verse if it stopped there. It does not stop there. In the same line, having said that we are driven by our past, Guru Nanak turns and praises God. Your goodness has no end. The line looks down at the path, and then it looks up.