Johannes Phocylides Holwarda

[2] Born in Holwerd, he is best remembered for his discovery of the length of Mira's (Omicron Ceti's) varying appearance cycle.

In a systematic study in 1638, he found that Mira disappeared and reappeared in a varying cycle of about 330 days.

His Philosophia Naturalis, seu Physica Vetus-Nova, published posthumously in 1651, defines matter and form: matter is extended and divided into atoms while form is the texture of atoms.

Atoms, which he distinguished as simple or compound, are solid corpuscles that receive motion directly from God.

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