“R Chanina said – A person should not pray in a room without windows”
Prayer is indeed a spiritual labor unique in the soul of one praying. However, the necessary condition for it to successfully effect the one praying, is the full knowledge of the value of the outside world. Then the perfect pleasantness will really have influence upon the one praying. However, for the person who’s individual prayer causes him to separate himself from the outside world, he will not arrive at the end purpose of prayer – which is to invigorate man to be ready to work with integrity and honesty according to the spirit of G-d that inspires him. Therefore, a person should only pray in a house that has windows, because the option of being able to see the outside world will inspire him to fulfill his duty to the world that he lives in….
The Kuzari – Communal Prayer
The Khazar king: Why is this? If everyone read his prayers for himself, would not his soul be purer and his mind less abstracted?
The Rabbi: Common prayer has many advantages. In the first instance a community will never pray for a thing which is hurtful for the individual, while the latter sometimes prays for something [to the disadvantage of other individuals, or some of them may pray for something] that is to his disadvantage. One of the conditions of prayer, craving to be heard, is that its object be profitable to the world, and not hurtful in any way. Another is that an individual rarely accomplishes his prayer without slips and errors. It has been laid down, therefore, that the individual recite the prayers of a community, and if possible in a community of not less than ten persons, so that one makes up for the forgetfulness or error of the other. In this way [a complete prayer is gained, read with unalloyed devotion. Its blessing rests on everyone] each receiving his portion. For the Divine Influence is as the rain which waters an area (if deserving of it), and includes some smaller portion which does not deserve it, but shares the general abundance…
A person who prays but for himself is like one who retires alone into his house, refusing to assist his fellow-citizens in the repair of their walls. His expenditure is as great as his risk. He, however, who joins the majority spends little, yet remains in safety, because one replaces the defects of the other. The city is in the best possible condition, all its inhabitants enjoying its prosperity with but little expenditure, which all share alike.
In a similar manner, Plato styles that which is expended on behalf of the law, "the portion of the whole." If the individual, however, neglects this "portion of the whole" which is the basis of the welfare of the commonwealth of which he forms a part, in the belief that he does better in spending it on himself, he sins against the commonwealth, and more against himself. For the relation of the individual is as the relation of the single limb to the body. Should the arm, in case bleeding is required, refuse its blood, the whole body, the arm included, would suffer. It is, however, the duty of the individual to bear hardships, or even death, for the sake of the welfare of the commonwealth. He must particularly be careful to contribute his "portion of the whole," without fail. (III, 18-19)