Obstacle to spiritual life
Devotees would often come to Sri Ramakrishna unable to find a way out of their existential problems. They would often ask Sri Ramakrishna as to why they are unable to progress in spiritual life in spite of their spiritual striving or Sadhana. Sri Ramakrishna would answer them patiently using a beautiful analogy. He would ask, how does one insert a thread in a needle. One has to take a fine thread and ensure that it is free from any extra fiber, etc and then carefully insert it into the hole in the needle. Even if a single fiber is sticking out, it is not possible to insert the thread into the needle. Thus, Sri Ramakrishna would say that human beings lead a life completely dominated by the senses. Their minds are full of desires largely based on lust and lucre.
At the same time, some people who have spiritual inclinations also try to perform Sadhana or spiritual disciplines. But, because of the fibers of desire that are sticking out, it is not possible for such people to enter the kingdom of God. It is similar to row a boat which is completely anchored. However much one may row, the boat will not move even an inch.
Similarly, the mind anchored to the world by the desire for enjoyments cannot progress in spiritual life. It is not possible for a mind full of desires to think of God or evolve spiritually.
But, through constant striving and also by disciplines such as Viveka, Vichara and Vairagya i.e. discrimination, enquiry and dispassion it is possible to slowly remove the encrustations of desires on our minds.
Of course, again and again one may slip or slide down, but one should not give up. By relentless and steadfast practice with a focused mind, over a long period of time it is possible to make a slow and steady, but sure Godward progress.