We have another metaphor here that compares freedom to a "strong seed." Notice the alliteration there too, with the beginning S sound in "strong" and "seed." But why a seed? What are some connotations for the words "strong seed"?
We might think of beginnings, strong beginnings, and the hope that the seed will flourish into something much bigger and more fruitful than its initial form. Maybe there's a potential for an even greater "strength" to come in that tiny little seed.
And if we think of freedom, the same kinds of ideas may come to mind. Freedom, as an ideal, provides the opportunity for bigger and better things beyond itself, perhaps in the sense of progress for an entire community or nation.
Since freedom is also planted here "in a great need," we also understand that freedom is not optional. It's necessary—just like the bread we saw earlier. So the speaker is really stressing the idea of freedom being a fundamentally necessary part of human life and, more specifically, democracy.
The perfect rhyme here with "seed" and "need" also carries the message behind freedom's "strong seed" even further, since rhymes tend to stick in our mind's ear (if you can imagine that) quite easily, like these sounds do here.