Dixon G. Watts, the 19th Century speculator (one of history's best and most respected), was a man of great wisdom:
It is better to act on general than special information (it is not so misleading), viz., the state of the country, the condition of the crops, manufacturers, etc. Statistics are valuable, but they must be kept subordinate to a comprehensive view of the whole situation.
A man must think for himself, must follow his own convictions. George MacDonald says: “A man cannot have another man’s ideas any more than he can another man’s soul or another man’s body.” Self-trust is the foundation of successful effort.
That equipoise, that nice adjustment of the faculties one to the other, which is called good judgment, is an essential to the speculator.