Explain the necessary conditions of passivity and activity between those working together. Though the best results are often obtained by you alone, yet the testimony of one person is not so convincing as the testimony of several who have witnessed and taken part in the same phenomena. But you are right in hesitating to take on the psychic conditions of insincere and merely curious people who would like to work with you. The great difficulty with most persons is that they cannot make themselves sufficiently negative _for the time being_. When the experiments are over they can and should become equally positive. They can shift from one pole to the other, and they must do so if they wish to preserve their physical health and balance. But bear in mind that the influences from this side are good and bad, even as the influences in the world are; and if you feel that any “presence” is hostile, at once banish it and become positive. After any approach by an undesirable influence, you should not for some hours let yourself become negative. Go for a walk, or attack some difficult piece of work, or read a book that demands mental activity in order to grasp its meaning. You live in a sea of mind, as well as in a psychic sea; they interpenetrate, and they interpenetrate with the physical; but in working through and with them, keep them as distinct as possible. I work more and more in the mental world, and less and less in the astral; but the majority of my readers will not know exactly what I mean by that statement. There is a greater difference between the astral and the mental than there is between the astral and the physical. Do not despise the astral. Its dynamics are of colossal import. But cultivate more and more the purely mental, because the astral in all of you is developed beyond the mental. In my former writings I have told you something of the dangers of the astral. Now I want to tell you some of the more obvious dangers of the mental. Those who learn that they can create in mind need to develop a sense of responsibility. They are too reckless in demonstrating their power. Remember that as you go up in the planes of being you get into subtler and subtler regions, and strength increases with the degree of subtlety--not the reverse, as you would naturally suppose. One of the greatest temptations of the mental world is that of the creation of falsehoods. By stating that which is not true, you project into the realm of mind a picture that has a certain permanency. It may deceive others, but in time it will deceive you, its creator. Those who speak falsely cannot perceive truth. Those who create false pictures in the mental world will be deceived by those very pictures; they will reap the effects of the causes they have set up.