集中力は力となる。 the concentration is the power.

Do not store in your brain useless information. Learn to unmind the mind. Unlearn whatever has been of no use to you. Then only can you fill your mind with divine thoughts. You will gain new mental strenght as the dissipated mental rays are collected now.
Swami Sivananda ---Thought Power p20


思考エネルギーを管理すること。conservation of thought-energy.

In physics you have the term 'power of orientation'. Thought the mass of energy is there, the current will not flow. It must be connected to the magnet and then the electric current will flow through the power of orientation. Even so, the mental energy which is dissipated and misdirected in various worthless worldly thoughts should be well directed in proper spiritual channels.
Swami Sivananda ---Thought Power p21


感情移入の悪影響 the bad influence on the empathy.

One should be in tune with the mental vibrations or thought-vibrations of another. Then only can one easily understanding another. Lustful thoughts, thoughts of hatred, jealousy and selfishness produce distorted images in the mind and cause clouding of understanding, perversion of intellect, loss of memory and confusion in the mind.
Swami Sivananda ---Thought Power p21


友情が成立しないのがもともとの個性によること Every man has his own mental world

Every man has his own mental world, his own mode of thinking, his own ways of understanding things and his own ways of acting. Just as the face and voice of every man differ from those of another man, the mode of thinking and understanding also differs. That is the reason why misunderstanding easily occurs between friends. One is not able to understand rightly the views of another. Hence friction, rupture and quarrel occur within a minute even amongst fast friends. The friendship does not last long.
Swami Sivananda ---Thought Power p20


良き思考で満たされていれば悪が介入する余地はない。there is no evil if your thought is fulfill of goodwill.

Unconsciously all people who are like you take the thought you have projected and in accordance with the capacity that they have, they send out similar thoughts. The result is work, you will be setting in motion great forces whoch will work together and put down the lowly and mean thoughts generated by the selfish and the wicked.
Swami Sivananda ---Thought Power p20


思考のすべてが不滅のもの。every thought is never perish.

Every thought that you send out is a vibration which never perishes. It goes on vibrating every particle of the universe and if your thoughts are noble, holy and forcible, they set in vibration every sympathetic mind.
Swami Sivananda ---Thought Power p20


適切さについてシヴァナンダ師の言及 Swami Sivananda mentioned to the proper.

Just as you take physical exercises, play games such as tennis and cricket in order to maintain physical health, you will have to maintain mental health by radiating the right thought-waves, by taking Sattvic food, mental recreation of an innocent and harmless nature, change of mood, relaxation of mind by entertaining good, ennobling and sublime thoughts and by cultivating the habit of cheerfulness.
Swami Sivananda ---Thought Power p20