Such observations should cover everything about the child--his movements, cries, impulses, sleep, dreams, personal preferences, muscular efforts, attempts at expression, games, favourites, etc .-- and should be recorded in a regular daybook at the time of occurrence.

What is important and what is not, is, as I have said, something to be learned; and it is extremely desirable that any one contemplating such observations should acquaint himself beforehand with the principles of general psychology and physiology, and should seek also the practical advice of a trained observer.
As yet many of the observations which we have in this field were made by the average mother, who knows less about the human body than she does about the moon or the wild flowers, or by the average father, who sees his child for an hour a day, when the boy is dressed up, and who has never slept in the same room with him--let alone the same bed!--in his life; by people who have never heard the distinction between reflex and voluntary action, or that between nervous adaptation and conscious choice.

The difference between the average mother and the good psychologist is this: she has no theories, he has; he has no interests, she has.

She may bring up a family of a dozen and not be able to make a single trustworthy observation; he maybe able, from one sound of one yearling, to confirm theories of the neurologist and educator, which are momentous for the future training and welfare of the child.
As for experimenting with children, only the psychologist should undertake it.

The connections between the body and the mind are so close in infancy, the mere animal can do so much to ape reason, and the child is so helpless under the leading of instinct, impulse, and external necessity, that the task is excessively difficult--to say nothing of the extreme delicacy and tenderness of the budding tendrils of the mind.