Today has in part included fighting the eternal losing battle against spotted knapweed, an invasive pioneer species that loves to sprout up in bad soil, suck up all the water, and spread toxins that inhibit the growth of other more beneficial species. Then it spreads everywhere.
A native to eastern Europe, the theory is that it was introduced in Washington State along with seeds for another crop some time in the 19th century. It has since spread to most of the lower 48 States and into Canada.
The stuff seems resistant to most broad-spectrum herbicides, too, not that I recommend such methods in the first place. Roundup makes me sick to my stomach and gives me a headache even if I just encounter its lingering odor when driving past a field or lawn where it has been applied.
There are noxious ideas too that take root in the barren mind when good ideas have not been planted and strong critical thinking skills have not been cultivated. These ideas become cherished ideologies that poison the mind against better ideas regardless of their merits. Some people will ignore all rational arguments and evidence contrary to their noxious ideas. And these ideas can spread rapidly, especially when foisted on the young or surreptitiously piggybacked in with other, better ideas.
As with the weed, care must be taken when encountering bad ideas. Fortunately, the truth can be an effective preventative and remedial solution. Care must be exercised in how it is applied, though. Unlike soil, a human has emotions that must be considered, and each individual needs time and space to process new thoughts. If they are receptive to truth, they will come around in their own time.
Be willing to examine your own thoughts regularly and carefully, too. We're all infested with bad ideas. Better to catch them early if possible. Be willing to engage in polite discussion with others about the ideas that matter most. Politics, religion, economics, philosophy, and emotion should not always be avoided in civil discourse.
Iron sharpeneth iron; so a man sharpeneth the countenance of his friend.
Proverbs 27:17 (KJV)