To study them is to learn both intuition and rigor. One must feel the sway — visualize fields oscillating, see nodal lines traced through space — and also wield equations that demand exactness. Boundary conditions become sentences in a logic of materials; eigenvalues and dispersion become the grammar of propagation. The thrill is in matching the picture in your mind to the crisp truth of math: to predict how a pulse will broaden in a fiber, how a waveguide will confine a mode, or how antennas can be shaped to whisper further and truer.