Only after the last tree has been cut down.  Only after the last river has been poisoned.  Only after the last fish has been caught.  Only then will you find that money cannot be eaten.

"When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. In this context the proponent of an activity, rather than the public, should bear the burden of proof." - Wingspread Statement of the Precautionary Principle.
Canada: