For this, the temper of the mind is essential. Every minute, from inside and outside, promptings and temptations arise and accumulate in man. He cannot attend to all these at the same time. So he fixes his attention on the most important among them only. This is called concentration, avadhana.
Concentration is needed to grasp any subject well.
Purposefully directing the attention on a subject and fixing it there is ekaagratha or one-pointedness. This is also a condition of the mind. Concentration and one-pointedness help to focus effort on any selected task.