Focus on his work on psychophysics and how he taught us that we could quantify aspects of the minds.
Western philosophy (inc. science and mathematics) had been struggling and disagreeing about the nature of our material and spiritual form.
Fechner offered a useful set of tools and possibilities to not only conceive of, but mathematically measure aspects of human consciousness.
Could and would psychology have been able to develop without this important steppingstone? Was it all Zeitgeist or was Fechner needed?
No right or wrong to the second part of this question, look at all the evidence and what we know about the development of science.
Include at least 4 relevant and peer-reviewed research articles in your essay. These can be experimental studies and/or reviews.