Every act of a man or animal, vertebrate or invertebrate, is based
upon either _reason_ or _hereditary instinct._ It is a
mistake to assume that because an organism is small it
necessarily has no "mind," and none of the propelling impulse that
we call thought. The largest whale may have less intelligence and
constructive reasoning than a trap-door spider, a bee or an ant.
To deny this is to deny the evidence of one's senses.

A MEASURE FOR ANIMAL INTELLIGENCE. The intelligence of an animal
may be estimated by taking into account, separately, its mental
qualities, about as follows:

1. General knowledge of surrounding conditions.
2. Powers of independent observation and reasoning.
3. Memory.
4. Comprehension under tuition.
5. Accuracy in the execution of man's orders.

Closely allied to these are the _moral qualities_ which go to
make up an animal's temperament and disposition, about as follows:

1. Amiability, which guarantees security to its associates.
2. Patience, or submission to discipline and training.
3. Courage, which gives self-confidence and steadiness.
4. A disposition to obedience, with cheerfulness.

All normal vertebrate animals exercise their intelligence in
accordance with their own rules of logic. Had they not been able
to do so, it is reasonable to suppose that they could never have
developed into vertebrates, reaching even up to man himself.