Why are Spanish adverbs formed using the feminine?

Question

To form adverbs in Spanish, you take your chosen adjective, e.g. **lent@** - *slow*, turn it into the feminine form, **lenta**, then add *-mente*, ***lentamente*** - *slowly*.Why do you use the feminine form here?In most gender-neutral cases, Spanish takes the masculine form, but this doesn't, why not?

Answer 1

It has to do with how the adverb evolved in Spanish. The Spanish adverb comes from people saying they were doing something 'mindedly', using the word 'mind': la mente. So it's feminine since the word 'mind' is feminine.