2 Metaphors for tenacity

TENACITY OF LIFE IN THE EEL.There is no fish so tenacious of life as this.

For they love the parade of formal reason, as they love big words or technical terms, or a smattering of French or Latin, with all the delight of a child in the mysterious and unfamiliar; but their pretence to be ruled by it is mere affectation, and the tenacity with which they cling to their arguments is rather the tenacity of blind faith in a dogma, than of clear insight into principles.

2 Metaphors for  tenacity