Darkness cannot be removed physically; it can only be removed by switching light or going into sunlight or lighting fire. Similarly negative thoughts are absence of positive thoughts.
In Bhagavad Gita also it has been said that the period of Uttarayana with longer days, the first half at full moon, in the presence of light or agni, one acquires more positive thoughts as compared in Dakshinayana before Amavasya or no moon or in absence of light.
Bhagavad Gita also says that whatever you think the whole life, you think at the time of death and if the time at the time of death you have positive thoughts, you are likely to get Moksha. That may be the reason why in Hindu mythology it is said that just before the death, we should light a diya or chant in front of agni (fire) so that dying person’s thoughts become positive.
In computer language, it is explained that when you open a file repeatedly, it becomes a priority file and comes in search engine on priority as compared to other files.

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